This comprehensive textbook is divided into sections that correspond to the eight areas of certifications as specified by the National Institute for Automotive Service Excellence (ASE) and the National Automotive Technicians Education Foundation (NATEF). The areas of the ASE material certification test are listed in the objectives at the beginning of each chapter, and all laboratory worksheets are correlated to the NATEF Task List.

A COMPLETE INSTRUCTOR AND STUDENT SUPPLEMENT PACKAGE This book is accompanied by a full set of instructor and student supplements. Please see page v for a detailed list of supplements.

A FOCUS ON DIAGNOSIS AND PROBLEM SOLVING The primary focus of this textbook is to satisfy the need for problem diagnosis. Time and again, the author has heard that technicians need more training in diagnostic procedures and skill development. To meet this need and to help illustrate how real problems are solved, diagnostic stories are included throughout. Each new topic covers the parts involved as well as their purpose, function, and operation, and how to test and diagnose each system. The following pages highlight the unique core features that set this book apart from other automotive textbooks.

Henry Ford (1863–1947) built his first car, called the Quadricycle. SEE FIGURE 1–1.

1900

About 4,200 total automobiles were sold, including:

HISTORICAL BACKGROUND For centuries, man either walked or used animals to provide power for transportation. After the invention of electric, steam, and gasoline propulsion systems, people used self-propelled vehicles, which are vehicles that moved under their own power. Major milestones in vehicle development include: 1876

The OTTO four-stroke cycle engine was developed by a German engineer, Nikolaus Otto.

1885

The first automobile was powered by an OTTO cycle gasoline engine designed by Karl Friedrick Beary (1844–1929).

1892

Rudolf Diesel (1858–1913) received a patent for a compression ignition engine. The first diesel engine was built in 1897.

REAL WORLD FIXES present students with actual automotive service scenarios and show how these common (and sometimes uncommon) problems were diagnosed and repaired.

Oldsmobile, founded by Ransom E. Olds (1864–1950), produced the first large-scale, affordable vehicle.

1908

William Durant (1861–1947) formed General Motors.

1908

The Ford Model T was introduced.

AUTOMOTIVE BACKGROUND AND OVERVIEW

A radio failed to work in a vehicle that was outside during a thunderstorm. The technician checked the fuses and verified that power was reaching the radio. Then the technician noticed the antenna. It had been struck by lightning. Obviously, the high voltage from the lightning strike traveled to the radio receiver and damaged the circuits. Both the radio and the antenna were replaced to correct the problem. SEE FIGURE 26–26.

1

OBJECTIVES AND KEY TERMS

appear at the beginning of each chapter to help students and instructors focus on the most important material in each chapter. The chapter objectives are based on specific ASE and NATEF tasks.

?

FREQUENTLY ASKED QUESTION

What Is an “SST?” Vehicle manufacturers often specify a special service tool (SST) to properly disassemble and assemble components, such as transmissions and other components. These tools are also called special tools and are available from the vehicle manufacturer or their tool supplier, such as Kent-Moore and Miller tools.

TECH TIP Right to TIghten Whenever removing any automotive component, it is wise to screw the bolts back into the holes a couple of threads by hand. This ensures that the right bolt will be used in its original location.

FREQUENTLY ASKED QUESTIONS are based on the author’s own experience and provide answers to many of the most common questions asked by students and beginning service technicians.

NOTE:

Most of these “locking nuts” are grouped together

and are commonly referred to as revailing torque nuts. This

TECH TIP

feature real-world advice and “tricks of the trade” from ASE-certified master technicians.

means that the nut will hold its tightness or torque and not loosen with movement or vibration.

NOTES

provide students with additional technical information to give them a greater understanding of a specific task or procedure.

SAFETY TIP Shop Cloth Disposal Always dispose of oily shop cloths in an enclosed container to prevent a fire. SEE FIGURE 1–69. Whenever oily cloths are thrown together on the floor or workbench, a chemical reaction can occur, which can ignite the cloth even without an open flame. This process of ignition without an open flame is called spontaneous combustion.

SAFETY TIPS

alert students to possible hazards on the job and how to avoid them.

iv

P REFACE

CAUTION: Never use hardware store (nongraded) bolts, studs, or nuts on any vehicle steering, suspension, or brake component. Always use the exact size and grade of hardware that is specified and used by the vehicle manufacturer.

CAUTIONS

alert students about potential damage to the vehicle that can occur during a specific task or service procedure.

WARNING REVIEW QUESTIONS 1. What are the typical operations needed when disassembling an automatic transmission/transaxle?

Do not use incandescent trouble lights around gasoline or other flammable liquids. The liquids can cause the bulb to break and the hot filament can ignite the flammable liquid which can cause personal injury or even death.

2. What are two methods of checking a clutch pack?

CHAPTER QUIZ

WARNINGS

alert students to potential dangers to themselves during a specific task or service procedure.

TRANSAXLE REMOVAL

1

For safety purposes, remove the negative battery cable before starting the removal procedure.

Remove engine bay cross members that may interfere with access to the transaxle fasteners.

7

Disconnect the lower ball joint on the front-wheel-drive vehicle to allow removal of the drive axle shaft.

8

1. Technician A says that the torque converter should be separated from the flex (drive) plate before removing the automatic transmission/transaxle. Technician B says that the clutches should be installed “dry” when replacing the frictions and steels in a clutch pack. Which technician is correct? a. Technician A only b. Technician B only c. Both Technicians A and B d. Neither Technician A nor B

6. Technician A says that the sharp edges of spool valves should be rounded, using 400 grit sandpaper. Technician B says that all valve body parts should be cleaned and then dried using low-pressure, filtered compressed air. Which technician is correct? a. Technician A only b. Technician B only c. Both Technicians A and B d. Neither Technician A nor B

7. Clutch pack clearance can be changed if not correct by using selective ______________. a. Piston b. Pressure plate c. Snap ring d. One of the above depending on the unit

3. Technician A says that all friction and steel plates in a clutch pack should be replaced during an overhaul. Technician B says that the automatic transmission fluid cooler should always be flushed when a unit is rebuilt or replaced. Which technician is correct? a. Technician A only b. Technician B only c. Both Technicians A and B d. Neither Technician A nor B

STEP-BY-STEP photo sequences show in detail the steps involved in performing a specific task or service procedure.

CHAPTER 130

THE REVIEW QUESTIONS AND CHAPTER QUIZ

at the end of each chapter help students review the material presented in the chapter and test themselves to see how much they’ve learned.

SUPPLEMENTS INSTRUCTOR SUPPLEMENTS

The instructor supplement package has been completely revamped to reflect the needs of today’s instructors. The Annotated Instructor’s Guide (ISBN: 0-13-255157-8) is the cornerstone of the package and includes:

Chapter openers that list:

— Safety Tips — Classroom discussion questions

Also included in the instructor supplement package are:

— NATEF/ASE tasks covered in the chapter

PowerPoint presentations

— All key terms

Image Library containing every image in the book for use in class or customized PowerPoints

SUPPLEMENTS (CONTINUED) To access supplementary materials online, instructors need to request an instructor access code. Go to www.pearsonhighered.com/ irc to register for an instructor access code. Within 48 hours of registering, you will receive a confirming e-mail including an instructor access code. Once you have received your code, locate your text in the online catalog and click on the Instructor Resources button on the left side of the catalog product page. Select a supplement, and a login page will appear. Once you have logged in, you can access instructor material for all Prentice Hall textbooks. If you have any difficulties accessing the site or downloading a supplement, please contact Customer Service at http://247.prenhall.com.

STUDENT SUPPLEMENTS Today’s student has more access to the Internet than ever, so all supplemental materials are downloadable at the following site for no additional charge: www. pearsoned.com/autostudent On the site, students will find:

The following people reviewed the manuscript before production and checked it for technical accuracy and clarity of presentation. Their suggestions and recommendations were included in the final draft of the manuscript. Their input helped make this textbook clear and technically accurate while maintaining the easy-to-read style that has made other books from the same author so popular. Jim Anderson Greenville High School Rankin E. Barnes Guilford Technical Community College

David W. Foor Columbus State Community College Kevin Ruby Chattahoochee Technical College John Gardner Chipola College Dennis A. Iudice KDI Automotive University William T. Reny Transportation Component Solutions, LLC

SPECIAL THANKS I also wish to thank Chuck Taylor, Blaine Heeter, and Mike Garblik from Sinclair Community College in Dayton, Ohio, for their help with many of the photo sequences. A special thanks to Dick Krieger for his detailed and thorough reviews of the manuscript before publication. Most of all, I want to thank my wife, Michelle Halderman, for her help in all phases of manuscript preparation. —James D. Halderman

P REF A C E

vii

ABOUT THE AUTHOR JIM HALDERMAN brings a world of experience, knowledge, and talent to his work. His automotive service experience includes working as a flat-rate technician, a business owner, and a professor of automotive technology at a leading U.S. community college for more than 20 years. He has a Bachelor of Science Degree from Ohio Northern University and a Masters Degree in Education from Miami University in Oxford, Ohio. Jim also holds a U.S. Patent for an electronic transmission control device. He is an ASE certified Master Automotive Technician and Advanced Engine Performance (L1) ASE certified. Jim is the author of many automotive textbooks all published by Pearson Prentice Hall Publishing Company. Jim has presented numerous technical seminars to national audiences including the California Automotive Teachers (CAT) and the Illinois College Automotive Instructor Association (ICAIA) as well as a member and presenter at the North American Council of Automotive Teachers (NACAT). Jim was also named Regional Teacher of the Year by General Motors Corporation and outstanding alumni of Ohio Northern University. Jim and his wife, Michelle, live in Dayton, Ohio. They have two children.

Henry Ford (1863–1947) built his first car, called the Quadricycle. SEE FIGURE 1–1.

1900

About 4,200 total automobiles were sold, including:

HISTORICAL BACKGROUND For centuries, man either walked or used animals to provide power for transportation. After the invention of electric, steam, and gasoline propulsion systems, people used self-propelled vehicles, which are vehicles that moved under their own power. Major milestones in vehicle development include: 1876

The OTTO four-stroke cycle engine was developed by a German engineer, Nikolaus Otto.

1885

The first automobile was powered by an OTTO cycle gasoline engine designed by Karl Friedrick Beary (1844–1929).

1892

Rudolf Diesel (1858–1913) received a patent for a compression ignition engine. The first diesel engine was built in 1897.

Oldsmobile, founded by Ransom E. Olds (1864–1950), produced the first large-scale, affordable vehicle.

1908

William Durant (1861–1947) formed General Motors.

1908

The Ford Model T was introduced.

AU T O MO T I V E BAC K G RO U N D A N D OVERVIEW

1

FIGURE 1–1 A Ford Quadricycle built by Henry Ford. 1912

The electric starter was invented by Charles F. Kettering (1876–1958) of Dayton, Ohio, first used on a Cadillac. The starter was produced by a new company called Delco, which stood for Dayton Electric Laboratories Company.

1914

First car with a 100% steel body was made by the Budd Corporation for Dodge. Before 1914, all car bodies had wood components in them.

1922

The first vehicle to have four-wheel hydraulically operated brakes was a Duesenberg built in Indianapolis, Indiana.

1940

The first fully automatic transmission was introduced by Oldsmobile.

1973

Airbags were offered as an option on some General Motors vehicles.

1985

Lincoln offers the first four-wheel antilock braking system.

1997

The first vehicle with electronic stability control was offered by Cadillac.

BODIES Early motor vehicles evolved from horse-drawn carriages. The engine and power train were attached to a modified carriage leading to the term “horseless carriage”. SEE FIGURE 1–2. The bodies evolved until in the 1930s, all-steel-enclosed bodies became the most used type. All bodies depended on a frame of wood or steel to support the chassis components.

CHASSIS SYSTEMS OVERVIEW

FIGURE 1–2 Most vehicle bodies were constructed with a wood framework until the 1920s.

FIGURE 1–3 A chassis of a 1950s era vehicle showing the engine, drivetrain, frame, and suspension. 3. The braking system of the vehicle is used to slow and stop the rotation of the wheels, which in turn stops the vehicle. The braking system includes the brake pedal, master cylinder, plus wheel brakes to each wheel. Two types of wheel brakes are used. Disc brakes include a caliper, which applies force to brake pads on both sides of a rotating disc or rotor. Drum brakes use brake shoes which are applied by hydraulic pressure outward against a rotating brake drum. The brake drum is attached to and stops the rotation of the wheels. Drum brakes are often used on the rear of most vehicles. 4. Wheels and tires—The wheels are attached to the bearing hubs on the axles. The tires must provide traction for accelerating, braking, and cornering, as well as provide a comfortable ride. Wheels are constructed of steel or aluminum alloy and mount to the hubs of the vehicle using lug nuts, which must be tightened correctly to the proper torque. The chassis components include:

The chassis system of the vehicle includes the following components: 1. Frame or body of the vehicle, which is used to provide the support for the suspension and steering components as well as the powertrain. 2. The suspension system of the vehicle, which provides a smooth ride to the driver and passengers and helps the tires remain on the road even when the vehicle is traveling over rough roads. The suspension system includes springs and control arms which allow the wheel to move up and down and keep the tires on the road.

2

CHAPTER 1

Front and rear suspension

Axles and hubs (to support the wheels and tires)

Steering mechanism

Engine and transmission

Final drive differential and axles

Often, these chassis were so complete that they could be driven without a body. FIGURE 1–3.

FIGURE 1–4 Body and terms. Many of the expensive automakers in the 1920s and 1930s had bodies built by another company. Eventually, most bodies were constructed of steel and many without the need for a frame to support the drivetrain and suspension.

BODY TERMS The roof of a vehicle is supported by pillars and they are labeled A, B, C, and D from the front to the rear of the vehicle. All vehicles have an A pillar at the windshield but many, such as a hardtop, do not have a B pillar. Station wagons and sport utility vehicles (SUVs) often have a D pillar at the rear of the vehicle. SEE FIGURE 1–4.

FRAMES Frame construction usually consists of channel-shaped steel beams welded and/or fastened together. Vehicles with a separate frame and body are usually called body-on-frame vehicles (BOF). Many terms are used to label or describe the frame of a vehicle including:

FIGURE 1–5 Note the ribbing and the many different pieces of sheet metal used in the construction of this body. TECH TIP

UNIT-BODY CONSTRUCTION

Unit-body construction (sometimes called unibody) is a design that combines the body with the structure of the frame. The body is composed of many individual stamped-steel panels welded together. The strength of this type of construction lies in the shape of the assembly. The typical vehicle uses 300 separate stamped-steel panels that are spot-welded together to form a vehicle’s body. SEE FIGURE 1–5. NOTE: A typical vehicle contains about 10,000 separate individual parts.

Treat a Vehicle Body with Respect Do not sit on a vehicle. The metal can easily be distorted, which could cost hundreds of dollars to repair. This includes sitting on the hood, roof, and deck (trunk) lid, as well as fenders. Also, do not hang on any opened door as this can distort the hinge area causing the door not to close properly.

AU T O MO T I V E BAC K G RO U N D A N D OVERVIEW

3

FIGURE 1–8 A Monroney label as shown on the side window of a new vehicle. FIGURE 1–6 A Corvette without the body. Notice that the vehicle is complete enough to be driven. This photo was taken at the Corvette Museum in Bowling Green, Kentucky.

?

FREQUENTLY ASKED QUESTION

What Is the Monroney Label? The Monroney label is the sticker on the vehicle that lists the manufacturer’s suggested retail price, usually abbreviated MSRP. The law that requires this label on all vehicles is called the Monroney Law, named for the congressman who sponsored the bill, Almer S. Monroney (1902–1980), a U.S. farm representative from Oklahoma from 1939–1951 and a U.S. Senator from 1951 to 1969. Before the Monroney label law was passed in 1958, the price of a vehicle was unknown to new vehicle buyers who had to rely on the dealer for pricing. Besides all of the standard and optional equipment on the vehicle, the Monroney label also includes fuel economy and exhaust emission information. SEE FIGURE 1–8.

FIGURE 1–7 A Ford flathead V-8 engine. This engine design was used by Ford Motor Company from 1932 through 1953. In a flathead design, the valves located next to (beside) the cylinders.

SPACE-FRAME CONSTRUCTION

Space-frame construction consists of formed sheet steel used to construct a framework of the entire vehicle. The vehicle is drivable without the body, which uses plastic or steel panels to cover the steel framework. SEE FIGURE 1–6.

ENGINE DESIGN EVOLUTION All gasoline and diesel engines are called internal combustion engines and were designed to compress an ignitable mixture. This mixture was ignited by using a spark (gasoline) or by heat of compression (diesel). Early engines used valves that were in the engine block, which also contained the round cylinders where pistons were fitted. The pistons are connected to a crankshaft, which converts the up and down motion of the pistons to a rotary force which is used to propel the vehicle.

4

CHAPTER 1

INLINE VERSUS V-TYPE DESIGN Most early engines used four or six cylinders arranged inline. These were called inline engines and are still produced today. Some engines with 4, 6, 8, 10, 12, or 16 cylinders were arranged with half of the cylinders on each set of a “V” and connected to a common crankshaft in the bottom of the “V.” The crankshaft changed the up-and-down motion of the piston to rotary motion, allowing the engine to power the drive wheels. VALVE LOCATION DESIGN

The design where the valves were located in the engine block is called flathead design because the cylinder head simply covered the combustion chamber and included a hole for the spark plug. The engine block contains passages for coolant as well as lubricating oil and is the support for all other engine systems. SEE FIGURE 1–7. By the 1950s, most engine designs placed the valves in the cylinder head. This is called an overhead valve or OHV design. Even newer engine designs feature overhead camshafts (OHC), called single overhead camshaft (SOHC) designs and engines that use two overhead camshafts per bank of cylinders called double overhead camshaft (DOHC) designs. The placement of the camshaft, which results in better flow of intake air into and exhaust out of the engine.

The need for reduced emissions and greater fuel economy led to advances in engine design. These changes included:

Electronic ignition systems

Electronic fuel injection

Computerized engine controls

Emission control devices, including the catalytic converter used in the exhaust system to reduce emissions

Improved engine oils that help reduce friction and reduce emissions

ENGINE SYSTEMS OVERVIEW

the electrodes of the spark plug ignites the air-fuel mixture in the combustion chamber and the resulting pressure pushes the piston down on the power stroke.

EMISSION CONTROL SYSTEM

The control of vehicle emissions includes controlling gasoline vapors from being released into the atmosphere in addition to reducing the emissions from the exhaust. Unburned gasoline emissions are called hydrocarbon (HC) emissions and exhaust gases that are controlled include carbon monoxide (CO) and oxides of nitrogen (NOX). The evaporative emission control system, usually called the EVAP system, is designed to prevent gasoline fumes and vapors from being released. Other emission control systems include:

Positive crankcase ventilation (PCV). This system uses a valve called a PCV valve to regulate the flow of gases created in the crankcase of a running engine, which are routed back into the intake manifold. The engine will then draw these gases into the combustion chamber where they are burned to help prevent the release of the gases into the atmosphere.

Exhaust gas recirculation (EGR). The EGR system meters about 3% to 7% of the exhaust gases back into the intake where the gases reduce the peak combustion temperature and prevent the oxygen (O2) and nitrogen (NO) from the air from combining to form oxides of nitrogen.

Catalytic converter. The catalytic converter is a unit located in the exhaust system usually close to the engine, which causes chemical changes in the exhaust gases.

On-board diagnostics means that the engine as well as the engine management systems can test itself for proper operation and alert the driver if a fault is detected. The warning lamp is called the malfunction indicator light (MIL) and is labeled “Check Engine” or “Service Engine Soon.” The onboard diagnostic system is currently in the second generation and is called OBD-II. Electronic hand-held testers, called scan tools, are needed to access (retrieve) stored diagnostic trouble codes (DTCs) and view sensor and system data.

Every engine requires many systems to function correctly.

COOLING SYSTEM While some older engines were air cooled, all engines currently in production are liquid cooled. Coolant is circulated by a water pump through passages in the cylinder block and head called water jackets. The coolant is a mixture of antifreeze and water to provide corrosion and freezing protection. After the coolant picks up the heat from the engine, it flows through a radiator, which cools the coolant by releasing the heat into the air. The temperature of the coolant is maintained by using a thermostat located in the coolant passage, which opens to allow coolant to flow to the radiator or closes until the coolant is hot enough to need cooling. LUBRICATION SYSTEM

All engines need a supply of lubricating oil to reduce friction and help to cool the engine. Most engines are equipped with an oil pan, also called an oil sump, containing 3 to 7 quarts (liters) of oil. An engine driven oil pump forces the oil under pressure through an oil filter, then to passages in the block and head called oil galleries, and then to all of the moving parts.

AIR INTAKE SYSTEM

All engines, both gasoline and diesel engines, draw air from the atmosphere. It requires about 9,000 gallons of air for each gallon of gasoline used. The air must be drawn where deep water in the road cannot be drawn into the engine. The air is then filtered by a replaceable air filter. After the air is filtered, it passes through a throttle valve and then into the engine through an intake manifold.

FUEL SYSTEM

POWERTRAIN OVERVIEW The purpose of the powertrain is to transfer the torque output of the engine to the drive wheels.

The fuel system includes the following compo-

nents and systems:

Fuel tank

Fuel lines and filter(s)

Fuel injectors

Electronic control of the fuel pump and fuel injection

REAR-WHEEL-DRIVE POWERTRAIN

A rear-wheel-drive vehicle uses the following components to transfer engine torque to the rear drive wheels:

Transmission. An automatic transmission usually uses planetary gearsets and electronic controls to change gear ratios. In a manually shifted transmission, the drivetrain contains a clutch assembly, which allows the driver to disengage engine torque from the transmission to allow the driver to shift from one gear ratio to another. The transmission contains gears and other assemblies that provide high torque output at low speeds for acceleration and lower torque output but at higher speeds for maximum fuel economy at highway speeds.

Drive Shaft. A drive shaft, also called a propeller shaft, is used to connect and transmit engine torque from the transmission to the rear differential. Universal joints (U-joints) are used to allow the rear differential to move up and down on the rear suspension and still be able to transmit engine torque.

The fuel injectors are designed to atomize the liquid gasoline into small droplets so they can be mixed with the air entering the engine. This mixture of fuel and air is then ignited by the spark plug.

STARTING AND CHARGING SYSTEM

Engine starting and charging systems, which include the battery, starting (cranking) system and charging system components and circuits.

IGNITION SYSTEM

The ignition system includes the ignition coil(s) which creates a high voltage spark by stepping up battery voltage using an ignition control module (ICM). The arc across

AU T O MO T I V E BAC K G RO U N D A N D OVERVIEW

5

FIGURE 1–9 A dash control panel used by the driver to control the four-wheel-drive system.

Differential. A differential is used at the rear of the vehicle and performs three functions:

Allows different axle speeds for cornering.

The differential increases the torque applied to the rear drive wheels by reducing the speed.

The differential also changes the direction of the applied engine torque and uses axle shafts to transfer the torque to the drive wheels.

FRONT-WHEEL-DRIVE POWERTRAIN

A front-wheel-drive vehicle uses a transaxle, which is a combination of a transmission and differential in one assembly. Drive axle shafts then transfer the engine torque to the front drive wheels from the output of the transaxle.

FOUR-WHEEL-DRIVE SYSTEM

There are many types of methods of powering all four wheels. Many include a transfer case to split engine torque to both the front and the rear wheels. SEE FIGURE 1–9.

ELECTRICAL/ELECTRONIC SYSTEMS OVERVIEW Early vehicles did not have an electrical system because even the ignition did not require a battery. Early engines used a magneto to create a spark instead of using electrical power from a battery as used today. The first electrical components on vehicles were batterypowered lights, not only for the driver to see the road, but also so others could see an approaching vehicle at night. Only after 1912 and the invention of the self-starter did the use of a battery become commonplace. Charles F. Kettering also invented the point-type ignition system about the same time as the self-starter. Therefore, the early batteries were often referred to as SLI batteries meaning starting, lighting, and ignition. From the 1920s into the 1950s other electrical components were added, such as radios, defroster fans, and horns. It was not until the 1960s that electrical accessories, such as air conditioning, power seats, and power windows, became common. Today’s vehicles require alternators that are capable of producing a higher amount of electricity than was needed in the past, and

6

CHAPTER 1

FIGURE 1–10 The alternator is in the heart of the electrical system.

the number of electronic components has grown to include every system in the vehicle, including:

A tire pressure monitoring system for the tires

Heated and cooled seats

Automatic climate control

Power windows

Security systems

Electric power steering

Electronic suspension

SEE FIGURE 1–10.

HEATING, VENTILATION, AND AIR CONDITIONING OVERVIEW Early model vehicles did not include any heaters or other methods to provide comfort for the driver and passengers. Most early vehicles were open with a simple removable top. Some had optional side curtains that provided all-weather protection. In the 1930s and 1940s when fully enclosed bodies became common, the vehicle manufacturers started to include heaters, which were small radiators with engine coolant flowing through them. About the same time and into the 1950s, about the only options that many vehicles had were a radio and heater, abbreviated R & H. Today, air-conditioning systems are on most vehicles and incorporate defrosters and passenger compartment heating, often in two zones for maximum comfort of the driver and passenger. Additional related comfort options today include heated and cooled seats and heated steering wheels.

EIGHT AREAS OF AUTOMOTIVE SERVICE In 1972, the National Institute for Automotive Service Excellence, a non-profit organization known as simply ASE, created a series of eight tests that cover the major vehicle systems. SEE FIGURE 1–11.

area are rear differential diagnosis and repair plus four-wheel-drive component diagnosis and repair.

SUSPENSION AND STEERING (A4) This content area includes steering and suspension system diagnosis and repair, including wheel alignment diagnosis and adjustments, and wheel and tire diagnosis and repair procedures. BRAKES (A5)

The brake content area includes the diagnosis and repair of the hydraulic system, drum and disc brake systems, plus power assist units, antilock braking, and traction control systems.

FIGURE 1–11 Test registration booklet that includes details on all vehicle-related certification tests given by ASE.

ELECTRICAL/ELECTRONIC SYSTEMS (A6) This content area includes many systems, including the battery, starting, charging, lighting, gauges, and accessory circuit diagnosis and repair. HEATING AND AIR CONDITIONING (A7)

ENGINE REPAIR (A1)

This content area includes questions related to engine block and cylinder head diagnosis and service, as well as the lubrication, cooling, fuel, ignition, and exhaust systems inspection and service.

AUTOMATIC TRANSMISSION (A2)

This content area includes general automatic transmission/transaxle diagnosis, including hydraulic and electronic related systems.

MANUAL DRIVE TRAIN AND AXLES (A3) This content area includes clutch diagnosis and repair, manual transmission diagnosis and repair, as well as drive shaft, universal, and constant velocity joint diagnosis and service. Also included in this content

The heating and air-conditioning content area includes air-conditioning service, refrigeration systems, heating and engine cooling systems diagnosis and repair, as well as refrigerant recovery, recycling, handling, and retrofit.

ENGINE PERFORMANCE (A8) The engine performance content area includes diagnosis and testing of those systems responsible for the proper running and operation of the engine. Included in this area are general engine diagnosis, ignition and fuel systems, as well as emission control and computerized engine control diagnosis and repair. This textbook covers the content of all eight ASE areas plus all of the background and fundamental information needed by technicians.

REVIEW QUESTIONS 1. In 1900, what was the most produced vehicle powered by?

5. The powertrain consists of what components?

2. What parts are included in the vehicle chassis?

6. What are the eight automotive service content areas?

3. Why were early engines called flat heads? 4. What is the difference between a unit-body and body-on-frame vehicle?

4. Early engines were called flat head design because they ______________. a. Were only inline engines b. Did not include valves c. Used valves beside the cylinder d. Used spark plugs at the top of the cylinders 5. A V-type engine could have how many cylinders? a. 4 c. 8 b. 6 d. All of the above 6. What component regulates the temperature of the coolant in an engine? a. Cooling (water) jackets c. Cooling fan(s) b. Thermostat d. Radiator

THE NEED FOR AUTOMOTIVE TECHNICIANS The need for trained and skilled automotive technicians is greater than ever for several reasons, including:

Vehicles are becoming more complex and require a higher level of knowledge and skills.

Electrical and electronic components and sensors are included throughout the vehicle.

Construction of parts and materials being used has changed over the last few years, meaning that all service work must be done to specified procedures to help avoid damage being done to the vehicle.

Increasing numbers of different types of lubricants and coolants make even routine service challenging.

All of the above issues require proper training and the ability to follow factory specified procedures to ensure customer satisfaction. The number of service technicians needed is increasing due to more vehicles on the road. A good service technician can find work in almost any city or town in the country, making the career as a professional service technician an excellent choice.

8

CHAPTER 2

THE NEED FOR CONTINUOUS VEHICLE SERVICE Vehicles are lasting longer due to improved materials and more exacting tolerances. Every year, vehicles are being driven farther than ever before. It used to be (in the 1950s) that the life of a vehicle was considered to be 100,000 miles or 10 years. Now achieving 200,000 miles without a major repair is common with proper maintenance and routine service. However, even the amount of needed routine service has been reduced due to changes in the vehicles, such as radial tires that now last 40,000 miles instead of older tires which were worn out and needed to be replaced every 15,000 miles.

WARRANTIES A warranty is a guarantee to the purchaser of a vehicle that it will function as specified. The warranty covers the quality and performance of the product and states the conditions under which the warranty will be honored. Vehicle warranties vary but all warranties indicate a time and mileage restriction. The expressed warranties often include the following areas:

New vehicle limited warranty that covers most components and is commonly called a bumper-to-bumper policy.

Powertrain warranty covers the engine, transmission/ transaxle, and final drive units. This coverage usually is longer than the bumper-to-bumper coverage.

Sheet metal rust through warranty is usually longer than the bumper-to-bumper and powertrain warranty and covers rust if a hole occurs starting from inside the outer metal surface of the body.

Emission control device warranties depend on the emission rating, the warranty coverage of the powertrain control module (PCM), and the catalytic converter and are covered for 8 years and 80,000 miles up to 10 years and 150,000 miles.

Vehicle warranties, unless an emergency repair, must be performed at a dealership, which is certified by the vehicle manufacturer to perform the repairs. At the dealership, the technician performing the repair must also be certified by the vehicle manufacturer. All technicians should be familiar with what may be covered by the factory warranties to help ensure that the customer does not have to pay for a repair that may be covered. While warranties do cover many components of the vehicle, wear and service items are not covered by a warranty in most cases and therefore, offer excellent opportunity for additional service work for trained automotive technicians.

FIGURE 2–1 A service technician checking for a noise of a vehicle in a new-vehicle dealership service department.

INCREASING AGE OF A VEHICLE

The average age of a vehicle on the road today has increased to older than nine years. This trend means that more vehicles than ever are not covered by a factory warranty and are often in need of repair. Aftermarket warranties also can be used at most repair facilities, making it very convenient for vehicle owners.

TECHNICIAN WORK SITES

FIGURE 2–2 A typical independent service facility. Independent garages often work on a variety of vehicles and perform many different types of vehicle repairs and service. Some independent garages specialize in just one or two areas of service work or in just one or two makes of vehicles.

Service technician work takes place in a variety of work sites including:

NEW VEHICLE DEALERSHIPS Most dealerships handle one or more brands of vehicle, and the technician employed at dealerships usually has to meet minimum training standards. The training is usually provided at no cost online or at regional training centers. The dealer usually pays the service technician for the day(s) spent in training as well as provides or pays for transportation, meals, and lodging. Most dealerships offer in house on-line training with minimum off-site training. SEE FIGURE 2–1. INDEPENDENT SERVICE FACILITIES

These small- to medium-size repair facilities usually work on a variety of vehicles. Technicians employed at independent service facilities usually have to depend on aftermarket manufacturers’ seminars or the local vocational school or college to keep technically up-to-date. SEE FIGURE 2–2.

MASS MERCHANDISER

Large national chains of vehicle repair facilities are common in most medium- and large-size cities. Some examples of these chains include Sears, Goodyear, Firestone, and NAPA, as shown in SEE FIGURE 2–3. Technicians employed by these chains usually work on a wide variety of vehicles. Many of the companies have their own local or regional training sites designed to train beginning service technicians and to provide update training for existing technicians.

FIGURE 2–3 This NAPA parts store also performs service work from the garage area on the side of the building.

SPECIALTY SERVICE FACILITIES Specialty service facilities usually limit their service work to selected systems or components of the vehicle and/or to a particular brand of vehicle. Examples of specialty service facilities include Midas, Speedy, and AAMCO Transmissions. Many of the franchised specialty facilities have their own technician training for both beginning and advanced technicians. SEE FIGURE 2–4. FLEET FACILITIES Many city, county, and state governments have their own vehicle service facilities for the maintenance and

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repair of their vehicles. Service technicians are usually employees of the city, county, or state and are usually paid by the hour rather than on a commission basis. SEE FIGURE 2–5.

TECHNICIAN JOB CLASSIFICATIONS There are many positions and jobs in the vehicle service industry. In smaller service facilities (shops), the duties of many positions may be combined in one job. A large city dealership may have all of the following vehicle service positions. A technician is often referred to as a tech.

LUBE TECH/QUICK SERVICE TECHNICIAN A lubrication technician should be trained in the proper use of hand tools and instructed how to properly service various types of vehicles. The training could be on-the-job (OTJ) or could be the result of high school or college automotive training. Some larger companies provide in-house training for new technicians and as a result they are trained to perform according to a specified standard. It is important that the lubrication technician double-check the work to be certain that the correct viscosity oil has been installed and to the specified level. The oil plug and oil filter must also be checked for leakage. Lubrication technicians are trained to perform routine services including:

Oil and oil filter change

Chassis lubrication

Fluids check and refill

Tire inflation checks

Accessory drive belt inspection

Air filter check and replacement

Cabin filter replacement

Windshield wiper blade replacement

As a result of these tasks the lubrication technician should be skilled in hoisting the vehicle and able to handle the tasks efficiently and in minimum time.

FIGURE 2–4 Midas is considered to be a specialty service shop.

NEW VEHICLE PREPARATION FOR DELIVERY A new entry-level position at a dealership often includes preparing new vehicles for delivery to the customer. This is often referred to as “new car prep.” The duties performed for new vehicle preparation are generally learned on the job. The vehicle manufacturer publishes guidelines that should be followed and it is the responsibility of the

FIGURE 2–5 A school bus garage is a typical fleet operation shop that needs skilled service technicians.

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new vehicle preparation person to see that all items are checked and serviced, and all associated paperwork is completed. The activities normally associated with preparing a new vehicle for delivery include:

Why Is the Work Order Important? The work order is a legal document that includes the description of the vehicle and the work requested by the customer. The customer then signs the work order authorizing that the stated work be performed. If there are additional faults found then the shop must notify the customer and get permission to change the amount or extent of the work originally authorized. As work is performed on the vehicle, the parts used and the labor operation performed are added. This creates a complete file on the repair. This means that the vehicle has to be properly identified by including the vehicle identification number (VIN) on the work order. There is only one vehicle with that VIN, yet there may be many “white Chevrolet pickup trucks.” The work order is the paper trail that shows all operations, labor times, and parts used when the vehicle was in control of the shop. A work order is often required even when the technician is working on his or her own vehicle.

NOTE: Many vehicle manufacturers ship the vehicles to the dealer with the tires overinflated to help prevent movement of the vehicle during shipping.

Checking all fluids

Checking that everything works including the remote key fob and all accessories

Ordering any parts found to be broken, missing, and damaged in transit

Removing all protective covering and plastic from the seats, carpet, and steering wheel

Washing the vehicle

GENERAL SERVICE TECHNICIAN A general service technician usually has training as an automotive technician either in one or more of the following:

High school—Technical or vocational school or a comprehensive high school that has an Automotive Youth Education System (AYES) program or NATEF certification.

College or technical school—Usually a two-year program that can earn the student an associate’s degree.

Career college or institute—Usually a 6-month to 12-month program earning the graduate a certificate.

Automotive service technicians perform preventative maintenance, diagnose faults, and repair automotive vehicles and light trucks. Automotive service technicians adjust, test, and repair engines, steering systems, braking systems, drivetrains, vehicle suspensions, electrical systems and air-conditioning systems, and perform wheel alignments. In large shops, some technicians specialize in repairing, rebuilding, and servicing specific parts, such as braking systems, suspension, and steering systems. In smaller shops, automotive service technicians may work on a wider variety of repair jobs. Automotive service technicians begin by reading the work order and examining the vehicle. To locate the cause of faulty operation and repair it, a technician will:

Verify customer concern

Use testing equipment, take the vehicle for a test-drive, and/ or refer to manufacturer’s specifications and manuals

Dismantle faulty assemblies, repair, or replace worn or damaged parts

Reassemble, adjust, and test the repaired mechanism Automotive service technicians also may:

may be required. The work is sometimes noisy and dirty. There is some risk of injury involved in working with power tools and near exhaust gases. SKILLS AND ABILITIES The work is most rewarding for those who enjoy doing precise work that is varied and challenging. Also, technicians usually achieve job security and a feeling of independence. To be successful in the trade, automotive service technicians need:

Good hearing, eyesight, and manual dexterity (ability to work with hands)

Mechanical aptitude and interest

The ability to lift between 25 and 50 pounds (11 and 25 kilograms)

The willingness to keep up-to-date with changing technology

A working knowledge of electricity, electronics, and computers is also required for many service procedures. EMPLOYMENT AND ADVANCEMENT. Automotive service technicians are employed by automotive repair shops, specialty repair shops, service facilities, car and truck dealerships, and by large organizations that own fleets of vehicles. Experienced automotive service technicians may advance to service manager or shop foreman. Some automotive service technicians open their own repair facilities. Many technicians can also start work in a shop or dealership and learn on the job. Most technicians keep up-to-date by attending update seminars or training classes on specific topics throughout the year. Specific tasks performed by a general service technician can include the following:

All of the tasks performed by the lubrication technician.

Engine repairs including intake manifold gasket replacement; cylinder head replacement; and oil and water pump replacement plus other engine-related tasks.

Brake system service and repair including disc brakes; drum brakes; parking brake; and antilock brake (ABS) diagnosis and service.

Advise customers on work performed, general vehicle conditions, and future repair requirements

WORKING CONDITIONS Most automotive service technicians work a 40-hour, five-day week. Some evening, weekend, or holiday work

FREQUENTLY ASKED QUESTION

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Suspension-related service including tire inspection and replacement; shock and strut replacement; servicing or replacing wheel bearings; performing steering component inspection and parts replacement; and performing wheel alignment and vibration diagnosis. Electrical-related diagnosis and repair including starting and charging problems; correcting lighting and accessory faults; and general service such as light bulb replacement and key fob reprogramming. Heating, ventilation and air conditioning work usually involves the use of diagnostic and service equipment that requires special training and certification if working with refrigerants. Engine performance-related diagnosis and repair including replacing fuel pumps and filters; cleaning or replacing fuel injectors; service ignition system components; solving emissions-related failures; and determining the cause and correcting “Check Engine” lights.

Manual transmission service and repairs including replacing clutches; adjusting, or replacing clutch linkage; and performing four-wheel-drive diagnosis and service procedures.

The vehicle is then driven by the service technician to verify the repair.

TECHNICIAN TEAM LEADER

A team leader is an experienced service technician who is capable of performing most if not all of the work that the shop normally handles. The team leader then assigns work to others in the group based on the experience or competency of the technician. The team leader then checks the work after it has been completed to be sure that it has been correctly performed. The number of hours of labor for each member of the team is totaled each pay period. Each member of the team is paid an equal share of the time but at different rates. The team leader gets a higher per hour rate than the others on the team. The rate of pay per hour is based on the level of training and experience. A beginning technician may or may not be paid as part of the total team hours depending on how the team system is organized. While some shops do not use teams, many large shops or dealerships have two or more teams. The advantage of a team-type organization is that everyone on the team looks out and helps each other if needed because they are all paid based on the number of hours the team generates. The team leader performs the duties of a shop foreman but only for those members on the team and not the entire shop. The team leader is under the direction and control of the service manager.

SHOP FOREMAN

A shop foreman (usually employed in larger dealerships and vehicle repair facilities) is an experienced service technician who is usually paid a salary (so much a week, month, or year). A shop foreman is a knowledgeable and experienced service technician who keeps up-to-date with the latest vehicle systems, tools, and equipment. Typical shop foreman’s duties include:

Assisting the service manager

Verifying that the repair is completed satisfactorily

The shop foreman is under the direction and control of the service manager.

SERVICE ADVISOR A service advisor, also called a service writer or service consultant, is the person at the dealership or shop designated to communicate the needs of the customer and accurately complete a work order. A service advisor should:

Have a professional appearance

Be able to speak clearly

Be able to listen carefully to the customer

Write neatly and/or type accurately

Be familiar with industry and shop standards and procedures

Most service advisors would benefit from taking a short course on service advising skill development and interpersonal relationship building. A service advisor should be familiar with the operation of the vehicle, but not to the same level as a service technician. A service advisor should not diagnose the problem, but rather state clearly on the work order what, when, and where the problem occurs so that the service technician has all the needed information to make an accurate diagnosis. SEE FIGURE 2–6 for an example of a typical work order. The service advisor’s duties include: 1. Recording the vehicle identification number (VIN) of the vehicle on the work order 2. Recording the make, model, year, and mileage on the work order 3. Carefully recording what the customer’s complaint (concern) is so that the service technician can verify the complaint and make the proper repair 4. Reviewing the customer’s vehicle history file and identifying additional required service 5. Keeping the customer informed as to the progress of the service work A service advisor must be at the shop early in the morning to greet the customers and often needs to stay after the shop closes for business to be available when the customer returns at the end of the day.

SERVICE MANAGER

The service manager rarely works on a vehicle but instead organizes the service facility and keeps it operating smoothly. A service manager can be a former service technician or in many larger dealerships, a business major graduate who is skilled at organization and record keeping. The service manager typically handles all of the paperwork associated with operating a service department.

NOTE: In a small shop, the shop owner usually performs all of the duties of a shop foreman and service manager, as well as the lead technician in many cases. Typical duties of a service manager include:

Establishing guidelines to determine the technicians’ efficiency

Supervising any warranty claims submitted to the vehicle manufacturer or independent insurer

Test-driving the customer’s vehicle to verify the customer concern (complaint)

Assigning work to the service technicians

Evaluating and budgeting for shop tools and equipment

Assisting the service technicians

Helps maintain the shop and shop equipment

Establishing service department hours of operation and employee schedules

TECH TIP Check the Vehicle before Work Is Started As part of the work order writing process, the service advisor should look over the vehicle and make a written note of any body damage that may already exist. If any damage is noted it should be mentioned to the customer and noted on the work order. Often the customer is not aware of any damage especially on the passenger side and thus would blame the shop for the damage after the service work was performed.

Assigning working hours and pay for technicians and others in the service department

must be able to greet and easily talk to customers and technicians. A parts counter person must also have computer skills and the willingness to help others. The parts counter person usually has the following duties:

Greet the customer or technician

Locate the correct parts for the service technician or customer

Suggest related parts (retail customers)

Stock shelves

Check in delivered parts

Take inventory

Keep the parts department clean

Help the parts manager

Establishing procedures and policies to keep the service area clean and properly maintained

SEE FIGURE 2–7.

PARTS MANAGER

The specific duties of a parts manager

usually include:

PARTS-RELATED POSITIONS The parts manager and other parts personnel such as the parts counter person are responsible for getting the correct part for the service technician.

PARTS COUNTER PERSON

A parts counter person often learns job skills by on-the-job training. A good parts counter person

Ordering parts from the vehicle manufacturers and aftermarket companies

Stocking parts

Organizing the parts department in a clear and orderly fashion

Locating parts quickly within the parts department

Developing contacts with parts departments in other local dealerships so that parts that are not in stock can be purchased quickly and at a reasonable cost

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FREQUENTLY ASKED QUESTION

What Is an Entrepreneur? An entrepreneur is a person who starts and operates a business. Many service technicians want to eventually own their own shop and become an entrepreneur. However, operating a shop involves many duties and responsibilities that many service technicians lack, including: • • • • • • • • •

FIGURE 2–7 Parts counter people need to know many aspects of automotive repair to be effective with customers.

While at first it may seem like owning your own shop would be great, a good technician can often make more money, and have fewer headaches, by simply working for someone else.

SALES JOBS—USED VEHICLES; NEW VEHICLES SALESPERSON When a vehicle is sold, it generates a potential customer for the service department. New and many used vehicle sales dealerships employ salespeople to help the customer select and purchase a vehicle. The salesperson should have excellent interpersonal skills, as well as be familiar with the local and regional laws and taxes to be able to complete all of the paperwork associated with the sale of a vehicle. The usual duties of a vehicle salesperson include:

Greet the customer Introduce yourself and welcome the customer to the store Qualify the customer as to the ability to purchase a vehicle

Demonstrate and ride with the customer on a test-drive

Be able to find the answer to any question the customer may ask about the vehicle and/or financing

Be able to complete the necessary paperwork

Follow up the sale with a telephone call or card

SALES MANAGER

A sales manager is an experienced salesperson who is able to organize and manage several individual salespeople. The duties of a sales manager include:

Establish a schedule where salespeople will be available during all hours of operation

A typical dealership includes many levels because there are many departments such as sales (new and used) as well as the service, parts and body shops to manage. SEE FIGURE 2–8.

INDEPENDENT SHOP.

An independent shop may or may not have a shop foreman depending on the number of technicians and the volume of work. Larger independent shops have a shop foreman, whereas at smaller shops, the owner is the shop foreman. SEE FIGURE 2–9.

DEALERSHIP PRINCIPAL (OWNER)

GENERAL MANAGER

SERVICE MANAGER

PARTS MANAGER

SHOP FOREMAN

SERVICE TECHNICIAN

BODY SHOP MANAGER

NEW VEHICLE MANAGER

USED VEHICLE MANAGER

PARTS RUNNER

PAINTER

OFFICE STAFF

OFFICE STAFF

COUNTER PERSON

BODY TECHNICIAN

SALESPEOPLE

SALESPEOPLE

SERVICE ADVISOR

FIGURE 2–8 A typical large new vehicle dealership organizational chart.

SHOP OWNER/MANAGER

OFFICE STAFF

SERVICE TECHNICIAN

FIGURE 2–9 A typical independent shop organizational chart.

REVIEW QUESTIONS 1. What should be included on a work order? 2. Why should a vehicle be inspected when the work order is being written? 3. What tasks are usually performed by a general service technician?

4. What duties are performed by the shop foreman and service manager? 5. What duties are performed by a parts counter person? 6. What duties are performed by vehicle salespeople?

CHAPTER QUIZ 1. A service advisor is called a ______________. a. Shop foreman c. Service writer b. Service manager d. Technician 2. What is not included on a work order? a. Customer’s mother’s maiden name b. VIN c. Mileage d. Description of work requested 3. All of the following are usual duties of a lube technician except ______________. a. Oil change c. Water pump replacement b. Air filter replacement d. Accessory drive belt inspection 4. New vehicle preparation is usually an entry-level vehicle service position and usually involves what duties? a. Installing dealer-installed options b. Correcting tire pressures c. Removal of all protective coverings and plastic d. All of the above 5. What is not a duty of a general service technician? a. Have the customer sign the work order b. Order the parts needed c. Diagnose the customer’s concern d. Perform vehicle repair procedures

6. Which description best fits the role of a service advisor? a. A skilled technician b. A beginning technician c. A customer service representative d. A money manager 7. Two technicians are discussing the duties of a shop foreman and a service manager. Technician A says that a shop foreman diagnoses vehicle problems. Technician B says that the service manager usually repairs vehicles. Which technician is correct? a. Technician A only c. Both Technicians A and B b. Technician B only d. Neither Technician A nor B 8. Who is the person that greets the service customer and completes the work order? a. Service manager c. Service writer b. Service advisor d. Either b or c 9. Which job would be concerned with the maintenance of the shop equipment? a. Service manager c. Shop owner b. Shop foreman d. Any ofw the above 10. Which job would be concerned with working hours and pay? a. Service manager c. Service advisor b. Shop foreman d. Service technician

If in Doubt, Ask No one expects a beginning service technician to know everything, but other technicians do not know what you do or do not know. It is usually assumed that the beginning technician will ask for help if they think they need the help. However, asking for help is very rare and requires the beginning technician to admit that they do not know something. Not asking for help can cause harm to the vehicle or the service technician. If in doubt— always ask. No one will be upset and learning the answer to your question will help in the learning experience.

DESIRE AND INTEREST

If a person has an interest in automobiles and trucks and likes computers, the automotive service field may be a good career choice. Computer skills are needed in addition to hands-on skills for several reasons, including:

Service information, such as diagnostic procedures and specifications, is commonly available in electronic format.

Work orders are commonly written and sent to the technician electronically. The technician therefore needs typing skills to type the steps taken during the service or repair procedures.

Hand tools and tool usage. Owning and experience using hand tools is important for a service technician. All service technicians are expected to be able to remove and replace parts and components as needed in a timely manner using proper tools and techniques.

Technical knowledge. While knowing how all aspects of the vehicle works is not expected of a beginning service technician, it is important that the technician have a basic understanding of the parts and procedures needed at least for routine service procedures.

Warranty claims are often submitted by the Internet and computer skills are needed to quickly and accurately submit claims and answer questions from the insurance company.

Interest in vehicles is also very important toward being successful as a professional service technician. Most technicians enjoy working on vehicles, not only professionally, but also during their spare time. Many technicians own a project vehicle, which could include:

Drag race vehicle

Race vehicle used in road racing

A fun vehicle used on sunny weekend days and evenings

Motorcycle

Snowmobile or jet ski

Truck for rock crawling

TECHNICAL KNOWLEDGE AND SKILLS The enjoyment of being involved with vehicles is very important because the job of servicing and repairing automobiles and trucks can be hard and dirty work. Many men and women enjoy being around and learning about the details of vehicle operation. With these desires and interest, working in the automotive service field is a great career. Technical information, skills, and tools needed include:

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JOB SHADOWING

A great way to see what it is really like to work as a service technician is to follow a professional around for a day or more. Job shadowing is usually arranged through an automotive program, and the shop or dealership has agreed to allow someone into the shop area to observe. While it does allow the student to observe, job shadowing does not allow the person to perform any work or help the technician in any way. During the day, the person who is job shadowing has to wear all personal protective equipment as required by the technician and must observe all safety regulations. The advantages of job shadowing include:

Being able to observe a typical day in the life of an automotive technician

Being able to talk to the working technician about what is being done and why

Being able to observe other technicians and seeing the various skill levels that often exist in a shop

COOPERATIVE EDUCATION PROGRAMS Cooperative education programs are formal programs of study at a high school or college where the student attends classes at the school, and also works at a local shop or dealership. If a cooperative education program is held at the high school level, the work at the shop or dealership occurs during the afternoon or evening and during the summer between the junior and senior year. The most common high school cooperative program is called AYES, which means Automotive Youth Education System (see www.ayes .org). The vehicle manufacturers involved in this program include:

DEVELOPING AN EMPLOYMENT PLAN An employment plan is an evaluation of your skills, interest, and talents. Selecting a career is different than getting a job. A typical job, while it does involve some training, usually can be learned in a few days to several months. However, a career requires many years to achieve competence. Therefore, selecting a career should require a thorough self-examination to determine what your true interest is in a particular career field. Some items that you should enjoy or would be willing and able to learn include:

Working with your hands, using tools and equipment

General Motors

Computer usage, including typing skills Working in an area where lifting is often required

Chrysler

Toyota

Honda

Being able to read, understand, and follow service information, technical service bulletins, and work orders

Nissan

BMW

Being able to perform diagnostic work and figure out the root cause of a problem

Kia

Subaru

Hyundai

If the cooperative education program is held at a community college, the work at the dealership occurs around the training sessions, usually the first or second half of a semester or on alternative semesters. The most common college programs include:

Another factory sponsored program open to those who have already completed a postsecondary automotive program is BMW STEP (Service Technician Education Program) (see www .bmwusa.com/about/techtraining.html).

APPRENTICE PROGRAMS An apprentice program involves a beginning service technician working at a shop or dealership during the day and attending training classes in the evening. The key advantage to this type of program is that money is being earned due to full-time employment and getting on-the-job training (OJT) during the day. Often the shop or dealership will help pay for training. While this program usually takes more than two years to complete, the work performed at the shop or dealership usually becomes more technical as the apprentice becomes more knowledgeable and gets more experienced. PART-TIME EMPLOYMENT

Working part time in the automotive service industry is an excellent way to get hands-on experience, which makes it easier to relate classroom knowledge to everyday problems and service issues. Working part time gives the student technician some flexibility as to college schedules and provides an income needed for expenses. Often part-time employment becomes full-time employment so it is important to keep attending technical classes toward becoming an asset to the company.

SOFT SKILLS In addition, any career, including being a service technician, requires many people skills, often called soft skills. These people-related skills include:

Working cooperatively with other people

Communicating effectively with others verbally (speech) and in writing

Working as a member of a team for the benefit of all

Being able to work by yourself to achieve a goal or complete a job assignment

Being able to lead or supervise others

Willingness to work with others with a different background or country of origin

While it is almost impossible to be able to answer all of these questions, just looking at these items and trying to identify your interests and talents will help in your selection of a career that gives you lifelong satisfaction.

LOCATING

EMPLOYMENT POSSIBILITIES Locating where you wish to work is a very important part of your career. Of course, where you would like to work may not have an opening and you may have to work hard to locate a suitable employer. First, try to select a shop or dealership where you think you would like to work because of location, vehicles serviced, or other factors. Ask other technicians who have worked or are presently working there to be sure that the location would meet your needs. If looking for employment through a want ad in a newspaper or employment Web site, check the following:

Job description. Is this a position that could advance into a more technical position?

Tools needed. Most professional service technician positions require that the technician provide their own tools. (The shop or dealership provides the shop equipment.) Do you have the tools needed to do the job?

Hours needed. Are you available during the hours specified in the ad?

Drug testing. Is a drug test needed for employment and are you prepared to pass?

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Educational Information

PREPARING A RESUME A resume is usually a one-page description of your skills, talents, and education. It is used by prospective employers to help narrow the field of applicants for a job or position. The number one purpose of a resume is to obtain a job interview. A good resume should include the following items:

Highest education level achieved

Major, if in a college or in a training program

Experience and Skills

Work or volunteer experience that may be helpful or useful to an employer. For example, if you took a course in welding, this may be useful to a shop owner who is looking for a service technician who could do welding, even though this fact was not included in the job posting.

A valid driver’s license is a must for most professional service technicians.

A good driving record. Often the shop insurance company will not allow a shop owner to hire a technician with a poor driving record.

Personal Information

Full given name (avoid nicknames)

Mailing address (do not use a post office [PO] box)

Telephone and/or cell phone number

E-mail address

Avoid using dates which could indicate your age

Sample Resume Personal Information: James Hartman 301 Main Street City, State 40005 Telephone: (555) 555-0170 Cell: (555) 555-1139 Career Goal: To become a certified ASE master technician and work at a new vehicle dealership. Experience: 2006 to the present—I work part time (20 hours per week) at Miller Service performing routine vehicle service, including oil changes, tire balancing, brake repairs, timing belt replacement, and intake manifold gasket replacement. I have assisted with suspension and air-conditioning repairs and own a basic set of hand tools. Education: High school diploma from Central High School, City, State 40010. I am finishing a two-year automotive technician training program at City College, City, State 40010 (to be completed May 15). Additional Training and Certification: ASE certified in Brakes and Engine Repair. Attended a seminar on wide-band oxygen sensors and electronic throttle control at a local automotive service exposition. Other Skills and Interests: I am restoring a 1969 Chevrolet Camaro, including all mechanical repairs and upgraded suspension system. References: Available upon request.

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REFERENCES

A reference is someone who is willing to tell a possible employer about you, including your skills and talents, as well as your truthfulness and work habits. Most employers would like to see someone who is familiar with you and your family, such as a priest, minister, or elder in your church. Some teachers or coaches also can be asked to be a reference. Always ask the person for approval before including the person on your list of references. Ask the reference to supply you with a written recommendation. Some references prefer to simply fill out a reference questionnaire sent by many companies. If a reference sends you a written recommendation, have copies made so they can be included with your resume.

PREPARING A COVER LETTER When answering an advertisement in a newspaper or magazine, be sure to include the details of where you saw the ad in your cover letter to the employer. For example: “I am applying for the position as an entry-level service technician as published in the August 15 edition of the Daily News.” If the requirements for the position are listed, be sure to include that you do have the specified training and/or experience and the tools needed for the job. If calling about a position, be sure to state that you are applying for the position posted and ask to speak to the correct person or to the person mentioned in the ad.

Sample Cover Letter

301 Main Street City, State 40005 Telephone: (555) 555-0170 Cell: (555) 555-1139 Date Mr. John Smith Smith Dealership 800 North Street City, State 40010 Dear Mr. Smith: I am applying for the position of general service technician at your dealership as advertised in the Sunday, January 7, edition of the Daily News. I am currently finishing my studies in Automotive Technology at City College and have worked part time at Miller Service for the past two years. I am ASE certified in Brakes and Engine Repair and plan to become certified in all eight areas. I have my own tools and currently can work in the afternoons and evenings. After May 15, I will be able to work full time after completing my automotive courses. I look forward to the opportunity to discuss my skills and resume in an interview. Thank you for your consideration. Sincerely, James Hartman Enclosure (1)

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TECH TIP Always Be Truthful No one is smart enough to be a liar. If you say something that is not true, then you have to remember what was said forever or your lie will often be discovered. If asked about your experience or knowledge, try to be as truthful as possible. Facts and skills can be learned and not knowing how to do everything that a shop may be involved with is not an indication that you will be rejected from the job opening.

Be clean shaven or have beard/mustache neatly trimmed

Have clean hair

Avoid facial jewelry

During the interview, try to answer every question honestly. Emphasize what you are capable of providing to the shop including:

Enthusiasm

Experience

Willingness to work

Willingness to work long hours and/or long weeks

AFTER THE INTERVIEW CONTACTING POTENTIAL EMPLOYERS When a job opening is posted in a newspaper or it is mentioned by a friend, most experts recommend that you visit the shop or dealership in person to see where the job is located, the condition of the buildings, and the surrounding areas. This trip could also be used for you to submit your resume and cover letter in person unless the company indicates otherwise. Be prepared to be interviewed when submitting your resume. Even if the position has already been filled, the trip gives you experience in meeting people and seeing the shop, which helps increase your confidence during the job search. Searching for a job is a full-time job in itself. Be prepared every day to answer ads, search employment web sites and travel to shops or dealerships.

COMPLETING THE EMPLOYMENT APPLICATION Most businesses require that an employment application be completed because it not only asks for all necessary personal information needed, but also references and emergency contacts. Most employment application forms ask for previous employers, the names and telephone numbers of contact people, and other information which you may not remember. It is wise to have all of the information written down ahead of time and take it with you for reference when completing the application. Always answer questions honestly and as thoroughly as possible. Never lie on an employment application.

After the interview, follow up with a letter thanking the shop for the interview. In the letter include when the interview occurred and that from the information you received, that you are very interested in becoming a part of the organization (shop or dealership). Also include contact information such as your cell phone number and e-mail address so the service manager can easily get in contact with you. A quick review of your skills and talent will also be helpful to the shop owner or service manager.

ACCEPTING EMPLOYMENT When a job is offered, there will likely be some paperwork that needs to be filled out and decisions made. Some of the requested information could include:

Social security number (social insurance number in Canada)

W-4 tax withholding form

Emergency contact people

Retirement plan selection (This is usually given to you to study and return at a later date.)

Other information which may be unique to the shop or dealership

After accepting the employment position, be sure to determine exactly what day and time you should report to work and try to determine where your tools should be placed. Most places will show you around and introduce you to others you will work with.

TECHNICIAN PAY METHODS THE INTERVIEW When meeting for the job interview, be sure to dress appropriately for the position. For example, a suit and tie would not be appropriate for an interview for a service technician position. However, the following may be a helpful guide:

Wear shoes that are not sneakers and be sure they are clean

Wear slacks, not jeans

Wear a shirt with a collar

Do not wear a hat

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STRAIGHT-TIME PAY METHODS

When the particular service or repair is not covered or mentioned in a flat-rate guide, it is common practice for the technician to clock-in and use the actual time spent on the repair as a basis for payment. The technician uses a flat-rate time ticket and a time clock to record the actual time. Being paid for the actual time spent is often called straight time or clock time. Difficult engine performance repairs are often calculated using the technician’s straight time.

FLAT-RATE PAY METHODS

Beginning service technicians are usually paid by the hour. The hourly rate can vary greatly

depending on the experience of the technician and type of work being performed. Most experienced service technicians are paid by a method called flat-rate. The flat-rate method of pay is also called incentive or commission pay. “Flat-rate” means that the technician is paid a set amount of time (flat-rate) for every service operation. The amount of time allocated is published in a flat-rate manual. For example, if a bumper requires replacement, the flat-rate manual may call for 1.0 hour (time is always expressed in tenths of an hour). Each hour has 60 minutes. Each tenth of an hour is 1/10 of 60 or 6 minutes.

slow time of year, maybe the technician will only have the opportunity to “turn” 20 hours per week. So it is not really the pay rate that determines what a technician will earn but rather a combination of all of the following:

Pay rate

Number of service repairs performed

Skill and speed of the service technician

Type of service work (a routine brake service may be completed faster and easier than a difficult engine performance problem)

0.9 hour ⫽ 54 minutes 1.0 hour ⫽ 60 minutes Many service operations are greater than 1 hour and are expressed as such: 2.4 hours ⫽ 2 hours and 24 minutes 3.6 hours ⫽ 3 hours and 36 minutes The service technician would therefore get paid the flat-rate time regardless of how long it actually took to complete the job. Often, the technician can “beat flat-rate” by performing the operation in less time than the published time. It is therefore important that the technician not waste time and work efficiently to get paid the most for a day’s work. The technician also has to be careful to perform the service procedure correctly because if the job needs to be done again due to an error, the technician does the repair at no pay. Therefore, the technician needs to be fast and careful at the same time. The vehicle manufacturer determines the flat-rate for each labor operation by having a team of technicians perform the operation several times. The average of all of these times is often published as the allocated time. The flat-rate method was originally developed to determine a fair and equitable way to pay dealerships for covered warranty repairs. Because the labor rate differs throughout the country, a fixed dollar amount would not be fair compensation. However, if a time could be established for each operation, then the vehicle manufacturer could reimburse the dealership for the set number of hours multiplied by the labor rate approved for that dealership. For example, if the approved labor rate is $60.00 per hour and: Technician A performed 6.2 hours ⫻ $60.00 ⫽ $372.00 Technician B performed 4.8 hours ⫻ $60.00 ⫽ $288.00 The total paid to the dealership by the ⫽ $660.00 manufacturer This does not mean that the service technician gets paid $60.00 per hour. Sorry, no! This means that the dealership gets reimbursed for labor at the $60.00 per hour rate. The service technician usually gets paid a lot less than half of the total labor charge. Depending on the part of the country and the size of the dealership and community, the technician’s flat-rate per hour income can vary from $7.00 to $20.00 or more per flat-rate hour. Remember, a high pay rate ($20 for example) does not necessarily mean that the service technician will be earning $800.00 per week (40 hours ⫻ $20.00 per hour ⫽ $800.00). If the dealership is not busy or it is a

GROSS VERSUS NET COMPENSATION Most beginning technicians start by receiving a certain amount of money per hours worked. Gross earnings are the total amount you earned during the pay period. The paycheck you receive will be for an amount called net earnings. Taxes and deductions that are taken from your paycheck may include all or most of the following:

In addition to the above, uniform costs, savings plan deductions, parts account deductions, as well as weekly payments for tools, may also reduce the amount of your net or “take-home” pay.

RETIREMENT INFORMATION AND PAYMENTS Some shops or dealerships offer some retirement savings plan but the most commonly used is an employer-sponsored 401(k) account named after a section of the U.S. Internal Revenue Code. A 401(k) account allows a worker to save for retirement while deferring taxes on the saved money and earnings until withdrawal. Most 401(k) plans allow the employer to select from stock mutual funds or other investments. A 401(k) retirement plan offers two advantages compared to a simple savings account.

The contributions (money deposited into the account) are tax deferred. The amount will increase due to interest and no taxes are due until the money is withdrawn.

Many employers provide matching contributions to your 401(k) account which can range from 0% (no matching contributions) to 100%.

The savings really add up over time. For example, if you start saving at age 25 and your income averages $3,000 per month ($36,000 per year) and you contribute 6% of your pay and the employer contributes 3%, after 40 years at age 65, the account will be worth $1,700,000 (one million, seven hundred thousand dollars) assuming a 10% average return. In retirement, most experts agree that 4% of the total can be withdrawn each year and not reduce the capital investment. Four percent of $1,700,000 is $68,000 per year or over $5,600 per month every month for the rest of your life.

ST ART I N G A C ARE E R I N T H E AU T O M OT IVE IN D U S T RY

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TECH TIP

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FREQUENTLY ASKED QUESTION

Hourly Rate to Annual Income

Where Does All the Money Go?

To calculate the amount of income that will be earned using an hourly rate, do the following:

Money earned does seem to quickly disappear. For example, if a soft drink and a bag of chips were purchased every day at work for $2.50, this amounts to $12.50 per week or $50 per month, which is $600 per year. Use the following chart to see where the money goes.

Multiply the hourly rate times 2 and then times 1000. For example: $10 per hour ⫻ 2 ⫻ 1000 ⫽ $20,000 per year. This easy-to-use formula assumes working eight hours an day, five days a week for 50 weeks (instead of 52 weeks in the year). The reverse can also be easily calculated: Divide the yearly income by 2 and then by 1000 ⫽ hourly rate For example: $36,000 per year ⫼ 2 ⫽ $18,000 ⫼1000 ⫽ $18 per hour

Income Labor rate per hour ⫻ number of hours worked ⫽ Overtime pay, if applicable ⫽ Part-time work on weekends ⫽ TOTAL WEEKLY INCOME ⴝ Multiply by 4.3 to get the MONTHLY INCOME ⫽

Many larger dealerships and service facilities often offer some or all of the following:

Not all service facilities offer all of these additional benefits.

HOUSING AND LIVING EXPENSES As a general guideline, housing expenses such as rent or a mortgage payment should not exceed 30% of the gross monthly income. For example, Ten dollars per hour times 40 hours per week ⫽ $400 per week times 4 weeks in a month ⫽ $1600 per month. Thirty percent of $1600 is $480 per month for rent or a mortgage payment. A vehicle payment should not exceed 25% of the gross earnings. In the example where the pay was $10 per hour, the maximum recommended vehicle payment should be $400 per month.

BECOMING A SHOP OWNER Many service technicians want to start and operate their own shop. Becoming a shop owner results in handling many non-automotiverelated duties that some technicians do not feel qualified to handle, including:

Handling customers

Ordering and paying for shop equipment and supplies

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Hopefully, the total income is more than the total expenses!

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FREQUENTLY ASKED QUESTION

Employee or Contract Labor? Most shops and dealerships hire service technicians as employees. However, some shops or businesses will pay a technician for services performed on a contract basis. This means that they are not hiring you as an employee, but simply paying for a service similar to having a plumber repair a toilet. The plumber is performing a service and is paid for the job rather than as an employee of the shop. An employer/employee relationship exists if the shop meets two factors: 1. Direction—This means that the employer can direct the technician to report to work to perform service work. 2. Control—This means that the employer can direct the hours and days when the work is to be performed and at the employer’s location. A contract labor association exists if the repairs are performed without both direction and control of the shop. If a contract labor basis is established, then no taxes are withheld. It is then the responsibility of the technician to make the necessary and required general tax payments and pay all taxes on time.

Bookkeeping, including payroll

Budgeting for and paying for garage owner’s insurance and workers’ compensation

Paying rent, as well as heat/air-conditioning bills

Advertising expenses

Hiring and firing employees

TECH TIP Find Three Key People An entrepreneur is a person who organizes and manages their own business assuming the risk for the sake of a profit. Many service technicians have the desire to own their own repair facility. The wise business owner (entrepreneur) seeks the advice of the following people when starting and operating their own business. 1. Attorney (lawyer) —This professional will help guide you to make sure that your employees and your customers are protected by the laws of your community, state, and federal regulations. 2. Accountant —This professional will help you with the journals and records that must be kept by all businesses and to help with elements such as payroll taxes, unemployment taxes, and workmen’s compensation that all businesses have to pay. 3. Insurance Agent —This professional will help you select the coverage needed to protect you and your business from major losses.

REVIEW QUESTIONS 1. What facts should be included on the resume?

4. What taxes are usually withheld from a paycheck?

2. What are five interviewing tips?

5. What are five duties of a shop owner?

3. What is the difference between gross pay and net pay?

CHAPTER QUIZ 1. A resume should be how many pages long? a. 1 b. 2 c. 3 d. 4 or more 2. What personal information should not be included on the resume? a. Address b. Cell or telephone number c. Age d. Work experience 3. Why is having a good driving record good for the shop? a. Allows the use of a company vehicle b. Lowers insurance costs c. Allows you to drive customers’ vehicles d. Permits you to use your vehicle to get parts 4. Which is not recommended during an interview? a. Wear shoes that are not sneakers b. Wear a shirt with a collar c. Have clean hair d. Wear jeans 5. During an interview, try to ________. a. Show enthusiasm b. Explain your work experience c. State your willingness to work d. All of the above

6. Ten dollars per hour is about how much income per year? a. $20,000 c. $30,000 b. $25,000 d. $35,000 7. One of the deductions from a paycheck is for Social Security. This item is usually shown on the pay stub as ________. a. Social Security b. SSA c. FICA d. U.S. government deduction 8. Technician A says that the net pay amount is usually higher than the gross pay amount. Technician B says that the gross pay amount is usually higher than the net pay. Which technician is correct? a. Technician A only b. Technician B only c. Both Technicians A and B d. Neither Technician A nor B 9. A beginning service technician earns $400 per week. How much should the technician spend on a vehicle payment? a. $400 per month c. $800 per month b. $500 per month d. $1000 per month 10. Which activity does not allow a person to perform any work while at the shop? a. Cooperative education program b. Apprenticeship program c. Job shadowing d. Part-time employment

Clean Clothes Are a Must Professionalism and personal credibility are important and can determine success as a service technician or as a customer service provider. A true professional does the following on a regular basis.

Anyone who meets the public in any business must not only be dressed appropriately, but the clothing should be clean. Service advisors and others that greet the public should also be sure that their shoes are shined. Dull, dirty, or scuffed shoes or messy appearance reflects an unprofessional look.

1. Practice consistency. Be positive, professional, and warm at all times. 2. Keep your word. Follow through with the commitments that you make. People will not have faith in you if you break your promises. 3. Develop technical expertise. Become very knowledgeable about the vehicles being serviced. Attend regular update training classes to keep up with the latest technical information and equipment. 4. Become a teammate with your co-workers. Working successfully with others shows that you have common goals and can benefit from the specific skills of others. 5. Be accountable. Practice honesty all of the time, admit mistakes, and take responsibility for actions. Apologize if you are wrong.

ETHICS

Ethics are a set of principles that govern the conduct of an individual or group. Sometimes ethical decisions are easy to recognize and are perceived as popular choices of behavior by the people around us. At other times the spectrum of potential choices falls into gray areas in which the “right” or “wrong” course of action is difficult or nearly impossible to identify. When faced with an ethically challenging situation, ask yourself the following questions:

Is it legal? (Is it against local, state, or federal laws?)

Is it fair? (Is it harmful to me or to others?)

How do I feel about it? (Is it against the teachings of my parents or my religion?)

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Would the court of public opinion find my behavior incorrect? (Would it disappoint my family?)

Am I fearful of what those I trust would say about my actions? (Would I be hurt or upset if someone did this to me?)

The above questions can be quite revealing when attempting to choose an ethical course of action.

COMMUNICATIONS The five main methods of communication used in effective customer service interaction include listening, talking, nonverbal communications, reading, and writing.

LISTENING

Active listening is the ability to hear and understand what the speaker is saying. To listen to your customers or other technicians is to show them that you care about and respect their questions and concerns. It is not easy to be a good listener; it takes practice and dedication to improve your listening techniques. Listening is a skill that must continuously be developed. Several barriers to good listening exist. A listener may be distracted from what is being said, have a closed mind to the speaker

TECH TIP Never Use Profanity Regardless of the situation, a true professional never resorts to the use of profanity. If tensions are high and the discussion becomes heated, try to defuse the situation by turning the situation over to someone else.

and the message, won’t stop talking, or is lazy and unwilling to make the commitment to be a good listener. Listening requires the listener to stop talking and to hear what the speaker is saying. It has been said that humans were given two ears and one mouth because we are supposed to listen twice as much as we speak. The best way to keep your mind focused on the speaker and to avoid becoming distracted is to pay attention. We can think about 10 times faster than we can speak, so frequently we have processed what speakers have said and are waiting for them to catch up with us. By focusing on speakers and on what is being said we are less likely to miss the messages being delivered. Putting that into practice is not as easy as it sounds. A good listener does the following:

Focuses on the speaker and what is being said.

Looks at the speaker and makes eye contact when possible.

Listens with an open mind.

Rephrases what was said to clarify that the intended message is understood.

A good listener knows the joy of sharing and communicating with others. Work to become the best listener you can be.

FIGURE 4–1 When answering the telephone, be sure to have paper and pen or pencil handy to record the customer information.

TECH TIP Always Have Paper and a Pen When on the Telephone When talking to a customer, whether in person or on the telephone, have paper and a pencil or pen to record the necessary information. In this case, the customer service representative at a dealer is using a preprinted form to record the service procedures to be performed on a customer’s vehicle while talking on the phone. SEE FIGURE 4–1.

TALKING

Talking means speaking, using words and terminology that others can comprehend. Eye contact is always important when we are communicating with others. Eye contact is allowing our eyes to make visual contact with someone else’s. In our culture, eye contact conveys sincerity and interest. Avoiding eye contact may suggest a lack of concern or lack of honesty. Customers may perceive that a customer service provider is not interested in what they are saying if they do not periodically make eye contact with the customer. When dealing with people from other cultures, customer service providers should be aware of cultural differences. In many other cultures eye avoidance is a sign of respect. Be sensitive to others but use eye contact whenever possible.

1. Ask questions, which would require them to pay attention plus it shows that you are interested in what they think. 2. Give the customer options rather than just ask them what they want such as saying “would you prefer to have this work done all at the same time or spread out over several weeks?”

TELEPHONE COMMUNICATION A large percentage of customers make first contact with a shop or dealer service department by telephone. Service technicians normally do not talk to customers directly but may be asked to help clarify a repair or a service procedure. Some suggestions when talking on the telephone include:

Use proper titles for the people with whom you communicate. If in doubt about whether to use a first name, call the person by the more formal Mr. or Ms. If they prefer the more informal first name, they will say so. It is better to be a little too formal than overly familiar.

Thank people for calling. “Thank you” is the most powerful phrase in human relations and it reassures customers that you are interested in serving.

Try to avoid technical terms and abbreviations such as EGR and other terms commonly used in the trade but will not be understood by the customer. Try to phrase the technical description by saying that you replaced or serviced a part in the emission control system and include the entire name of the part such as the “exhaust gas recirculation valve.”

The tone and inflection of the voice, facial expressions, posture, hand movements, and eye contact are all forms of nonverbal communications. These nonverbal indicators can contradict the message conveyed through another method of communication. Nonverbal communication includes body posture such as having the arms crossed. When a person crosses their arms, or looks at other things rather than paying attention to what you are discussing, these actions could indicate one of several things including: 1. They are not interested in what you are saying 2. They don’t believe what you are saying 3. They are not listening

If this type of nonverbal communication is noticed, there are several things that could be done to overcome this barrier including:

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TECH TIP Use Internet Translation If the customer is non-English speaking, type the information into a text document and search for a translation on the Internet. Give the copy of the translated document to the customer. The customer request could also be translated into English if needed to help the shop understand exactly what the customer is requesting and needs.

TECH TIP Google Is Your Friend

FIGURE 4–2 If you smile while talking on the telephone, your attitude will be transmitted to the customer.

If unsure as to how something works or if you need more detailed information about something, go to www.google .com® and search for the topic. Using the Internet can help with locating hard-to-find facts and can even be used to help with a service procedure that you have not done before. For a link to all factory service information, go to the Web site of National Automotive Service Task Force at www.nastf.org. Look at the work scheduled for the next day and try to determine as much about the job as possible so you can be prepared the next day to tackle the procedure. Using the International Automotive Technicians Network at www.iatn.net is also very helpful for technical information and can help pin down hard-to-find problems.

TECH TIP Smile While You Talk If you smile while talking on the telephone, your voice will reflect a positive and helpful attitude, which customers or vendors will easily recognize over the telephone. SEE FIGURE 4–2.

Avoid saying anything that makes people or your shop look unprofessional or uncaring. When dealing with customers, some words are more positive and appropriate to use. Some customer service providers find it helpful to list words to use and words to avoid on a card so that it is available for easy reference.

Speak clearly and distinctly. Hold the telephone mouthpiece about a half-inch from your lips. Speak naturally and comfortably. Talk to your caller as you would to a friend.

Move to a quiet area if background noise level is high.

service information that the wiring connector was “adjacent to the coolant reservoir.” The technician did not understand what the word adjacent meant and found out from another technician that it meant “next or close to.” If reading a note from a customer written in another language you do not understand try to ask if someone else in the shop can read it for you.

WRITING

Writing is communicating by using the written word so that others can understand the intended message. Service technicians are required to document the work that was performed on a vehicle. For some technicians this is the most difficult part of the service. If writing, be sure it is legible and if not, then print all messages and information. Writing or typing in the description of the steps performed during the diagnosis and repair of the vehicle should be worded as if the technician is talking to the customer. For example, if a coolant leak was repaired by replacing the water pump the technician should write out the following steps and operations on the work order:

WHAT HAPPENS THE FIRST DAY? The first day on the job, someone, usually the shop owner or shop foreman, should:

Introduce the new technician to key people at the shop.

1. Visually verified coolant leaking.

2. Performed a pressure test of the cooling system and located the leak as coming from the water pump.

Show the new technician the facility, parking, rules, and regulations of the organization.

Establish the new technician’s work area.

Ask questions of the new technician regarding their skills and talents.

3. Replaced the water pump and added new coolant and bled the system of trapped air. 4. Pressure tested the cooling system to verify that the leak was corrected—no leaks found.

READING

Reading means the ability to read and comprehend the written word. All service technicians need to be able to read, understand, and follow written instructions and repair procedures. If some words are not understood use a dictionary or ask another technician for help. For example, a beginning technician read in the

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The shop owner or foreman should:

Review the training tasks that were completed in school.

Try to direct work to the new technician that covers the new training material.

The first day on the job the beginning technician should:

Smile and ask questions if needed to clarify procedures and regulations.

TECH TIP

TECH TIP

Don’t Touch Other Technician’s Tools

If Late—Call

A beginning technician seldom has all of the tools needed to perform all of the service and repair tasks. A technician’s tools are very important. If a tool needs to be borrowed, the beginning technician should ask for permission to borrow a tool. Then when the tool is returned , it should be clean and replaced back exactly where the technician asks for it to be returned.

When running late, you may know that you will be just a few minutes late but your boss does not how late you will be. If you are going to be late, even by a few minutes, call the shop and let them know. This does not eliminate your being late from your record, but does demonstrate your concern to your service manager and other technicians who are counting on you to being on time to work every day.

TECH TIP

TECH TIP Regulated Terms to Use

Ask Me about This

In some states or areas where automotive service is regulated, such as in California or Michigan, it is important that the term used to describe a labor operation is the term defined by the state agency. This means that some terms used in parts and time guides may not be the same terms used by the state. Always check that the terms used are in compliance with all regulations. Some terms that could be affected include rebuild, repair, overhaul, inspection and R & R (remove and replace), and safety inspection.

A good service advisor will document what the customer wants done on the work order. However, there are times when the explanation and description would take too long and too much space to be practical. In these cases, the wise service advisor simply states on the work order for the service technician to see the service advisor to discuss the situation. The service advisor can write the basic request to document what is needed.

Be prepared to take and pass a drug test.

Assure the service manager or shop owner that you are serious about a career as an automotive technician.

A work order, also called a repair order or RO is assigned to a technician who is best qualified to perform the work. The technician gets the keys and drives the vehicle to an assigned service bay (also called a stall), performs the proper diagnosis, gets the necessary parts from the parts department, and completes the repair. After the service work has been performed, the service technician should then fill out the work order and describe what work was performed. These are called the “three Cs.” 1. Concern—Write on the work order what was done to confirm the customer’s concern. For example, “Drove the vehicle at highway speed and verified a vibration.” 2. Cause—The service technician should write the cause of the problem. For example, “Used a scan tool and discovered that cylinder #3 was misfiring.” 3. Correction—The service technician should write what was done to correct the problem. For example, “Removed the spark plug wire from cylinder number three and by visual inspection found that the boot had been arcing to the cylinder head. Replaced the spark plug wire and verified that the misfire was corrected.”

DUTIES OF A SERVICE TECHNICIAN READING THE WORK ORDER

A work order is selected or assigned to a service technician who then performs the listed tasks. The work order should be written so that the technician knows

exactly what needs to be done. However, if there is any doubt, the technician should clarify the needed task with the service advisor or the person who spoke to the customer.

TALKING TO CUSTOMERS The typical service technician usually does not talk directly to a customer except in some smaller shops. However, there may be causes where the technician will be asked to clarify a procedure or repair to a customer. Many technicians do not like to talk to the customers and fear that they may say too much or not enough. If a technician is asked to talk to a customer, try to keep the discussion to the following without being too technical.

The service technician should repeat the original concern. This is to simply verify to the customer and the technician the goal of the service or repair.

The cause of the fault should be mentioned. If further diagnostic steps needed to find the cause are requested, discuss the steps followed and the equipment or tools used.

Discuss what was done to solve the concern, including what part or parts were replaced. This step may also include what other service operations were needed to complete the repair, such as reprogramming the computer.

NOTE: If the customer speaks a foreign language that you do not understand, excuse yourself and locate someone in the shop who can assist you with communicating with the customer. Avoid using slang or abbreviation of technical terms. Ask the person if they understand and be willing to restate, if needed, until the situation is understood. This can often be difficult if discussing technical situations to persons of another language or culture.

ESTIMATING A REPAIR

Sometimes a service technician is asked to help create an estimate for the customer. It is usually the responsibility of the service advisor or shop owner to create estiates.

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TECH TIP Car, Truck, or Vehicle?

What Can a Service Technician Do to Earn More Money?

When discussing a vehicle with a customer, it is best to avoid creating problems. For example, if a technician asked about a customer’s “car,” the customer could become concerned because they drive a truck and many owners of trucks do not want their vehicle called a car. Use of the term “vehicle,” a generic term, is often recommended when talking to customers to avoid possible concerns.

Because service technicians are paid on a commission basis (flat-rate), the more work that is completed, the more hours the technician can “turn.” Therefore, to earn the most money, the service technician could do the following to increase the amount of work performed: • Keep up-to-date and learn the latest technical information • Practice good habits that help avoid errors or incomplete repairs • Learn from experienced and successful fellow technicians and try to approach the repair the same way the successful technician does • Purchase the proper tools to do the work efficiently

The technician may be helpful by pointing out all of the operations that need to be performed to achieve a repair. The estimate for a repair includes:

Parts needed—This list would also include any gaskets and/ or supplies needed. The technician can help identify if extra supplies may be needed.

Labor—A published time guide is usually used but many times options such as rear air conditioning or four-wheel drive may add substantial time to the operation. The technician can help with the estimate by making sure that the options are pointed out to the service advisor or shop owner.

DOCUMENTING THE WORK ORDER The service technician must document the work order. This means that the service technician must write (or type) what all was done to the vehicle including documenting defective components or conditions that were found in the course of the diagnosis. The documentation is often called “telling the story” and should include the following:

The test equipment used to diagnose the problem. For example: Used a Tech 2 scan tool to retrieve P0300 random misfire diagnostic trouble code.

Used a digital multimeter to determine a spark plug wire was defective.

List what parts or service operations were performed. For example: Replaced the spark plug wire on cylinder number 3. Used a scan tool to clear the diagnostic trouble codes and verify that the engine is operating correctly.

FOLLOWING RECOMMENDED PROCEDURES All service technicians should follow the diagnostic and service procedures specified by the vehicle manufacturer. Following service information procedures includes the following:

Follow and document the diagnostic procedure. Writing down the test results helps the customer see all that was involved in the procedure and creates the proper paper trail for future reference, if needed.

Follow the recommended removal and reinstallation (R & R) procedures. This step helps prevent the possibility of doing harm to the vehicle if an alternative method is attempted.

Always torque fasteners to factory specifications. This step is very important because under- or overtightened fasteners can cause problems that were not present until after the repair. The wise technician will document torque specifications on the work order.

NOTE: This does not mean that every technician needs to purchase all possible tools. Purchase only those tools that you know you will need and use.

the warranty. Often the same factory flat-rate number of hours is used to calculate the technician’s pay, but customer pay often pays the service technician at a higher rate. For example, a service technician earning $15.00 per flat-rate hour for warranty work may be paid $18.00 per hour for customer-pay work. Obviously, service technicians prefer to work on vehicles that require customer-pay service work rather than factory-warranty service work.

NONDEALERSHIP FLAT-RATE Technicians who work for independent service facilities or at other nondealership locations use one or both of the following to set rates of pay:

These guides contain service operation and flat-rate times. Generally, these are about 20% higher (longer) than those specified by the factory flat-rate to compensate for rust or corrosion and other factors of time and mileage that often lengthen the time necessary to complete a repair. Again, the service technician is usually paid a dollar amount per flat-rate hour based on one of these aftermarket flat-rate guides. The guides also provide a list price for the parts for each vehicle. This information allows the service advisor to accurately estimate the total cost of the repair.

FLAGGING A WORK ORDER When a service technician completes a service procedure or repair, a sticker or notification on the work order indicates the following:

Technician number (number rather than a name is often used not only to shorten the identification but also to shield the actual identity of the technician from the customer)

Work order number

CUSTOMER PAY

Customer pay (CP) means that the customer will be paying for the service work at a dealership rather than

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FREQUENTLY ASKED QUESTION

PARTS REPLACEMENT Parts replacement is often called R & R, meaning remove and replace. NOTE: R & R can also mean remove and repair, but this meaning is generally not used as much now as it used to be when components such as starters and air-conditioning compressors were repaired rather than replaced as an assembly.

FIGURE 4–3 Note the skill levels of the technician and the extra time that should be added if work is being performed on a vehicle that has excessive rust or other factors as stated in the time guide.

TECH TIP Technician Skill Level and Severe Service Most aftermarket service information includes a guideline for the relative level of the technician’s skill required to perform the listed service procedures. These include: A Highly skilled and experienced technician B Skilled technician who is capable of performing diagnosis of vehicle systems C Semi-skilled technician who is capable of performing routine service work without direct supervision Many time guides provide additional time for vehicles that may be excessively rusted due to climate conditions or have been subjected to abuse. Be sure to quote the higher rate if any of these conditions are present on the customer’s vehicle. SEE FIGURE 4–3.

Actual clock time from a time clock record for certain jobs as needed.

Amount of time allocated to the repair expressed in hours and tenths of an hour

The application of the service technician’s sticker to the back of the work order or completing the details of the repair into the electronic service record is called flagging the work order. NOTE: The actual assignment of the time is often done by another person at the dealership or service facility. This procedure assures that the correct number of hours is posted to the work order and to the technician’s ticket.

SUBLET REPAIRS Often a repair (or a part of a repair) is performed by another person or company outside of the dealership or service facility. For example, an engine needing repair that also has a defective or leaking radiator would be repaired by the original repair facility, but the radiator may be sent to a specialty radiator repair shop. The radiator repair cost is then entered on the work order as a sublet repair.

R & I is often used to indicate remove and inspect to check a component for damage. The old replaced part is often returned for remanufacturing and is called a core. A core charge is often charged by parts stores when a new (or remanufactured) part is purchased. This core charge usually represents the value of the old component. Because it is needed by the remanufacturer as a starting point for the remanufacturing process, the core charge is also an incentive to return the old part for credit (or refund) of the core charge. NOTE: Most parts stores today require that all cores be returned in the original boxes. Be sure to place the defective part into the same box that was used for the new or remanufactured part to be sure that the shop gets the proper credit for the core.

ORIGINAL EQUIPMENT PARTS

Parts at a new vehicle dealership come either directly from the vehicle manufacturer or a regional dealership. If one dealership purchases from another dealership, the cost of the part is higher, but no waiting is required. If a dealership orders a part from the manufacturer directly, the cost is lower, but there is often a 7- to 10-day waiting period. Original equipment parts, abbreviated OE, are generally of the highest quality because they have to meet performance and durability standards not required of replacement parts manufacturers. NOTE: Many service technicians will use only OE parts for certain critical systems such as fuel injection and ignition system components because, in their experience, even though the price is often higher, the extra quality seems to be worth the cost not only to the owner of the vehicle but also to the service technician who does not have to worry about having to replace the same part twice.

AFTERMARKET PARTS Parts manufactured to be sold for use after the vehicle is made are often referred to as aftermarket parts or renewal parts. Most aftermarket parts are sold at automotive parts stores or jobbers. A jobber or parts retailer usually gets parts from a large regional warehouse distributor. The warehouse distributor can either purchase parts directly from the manufacturer or from an even larger central warehouse. Because each business needs to make a profit (typically, 35%), the cost to the end user may not be lower than it is for the same part purchased at a dealership (two-step process instead of the typical three-step process) even though it costs more to manufacture the original equipment part. To determine what a 35% margin increase is for any product, simply divide the cost by 0.65. To illustrate how this works, compare the end cost of a part (part A) from a dealership and a parts store.

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Retail Parts Store

New Vehicle Dealership

Manufacturer’s selling price $17.00

Manufacturer’s selling price $25.00

Warehouse distributor’s selling price $26.15 ($17.00 0.65 $26.15)

Parts department selling price $38.46 ($25.00 0.65 $38.46)

TECH TIP Work Habit Hints The following statements reflect the expectations of service managers or shop owners for their technicians: 1. Report to work every day on time. Being several minutes early every day is an easy way to show your service manager and fellow technicians that you are serious about your job and career. 2. If you must be late or absent, call your service manager as soon as possible. 3. Keep busy. If not assigned to a specific job, ask what activities the service manager or supervisor wants you to do. 4. Report any mistakes or accidents immediately to your supervisor or team leader. Never allow a customer to be the first to discover a mistake. 5. Never lie to your employer or to a customer. 6. Always return any borrowed tools as soon as you are done with them and in clean condition. Show the person you borrowed the tools from that you are returning them to the toolbox or workbench. 7. Keep your work area neat and orderly. 8. Always use fender covers when working under the hood. 9. Double-check your work to be sure that everything is correct. a. Remember: “If you are forcing something, you are probably doing something wrong.” b. Ask for help if unclear as to what to do or how to do it. 10. Do not smoke in a customer’s vehicle. 11. Avoid profanity. 12. DO NOT TOUCH THE RADIO! If the radio is turned on and prevents you from hearing noises, turn the volume down. Try to return the vehicle to the owner with the radio at the same volume as originally set.

Retail store selling price $40.23 ($26.15 0.65 $40.23)

NOTE: The cost of the part to the customer where service work is performed is increased about 35% over the base cost of the part. For example, a part that cost the repair facility $40.23 will be billed to the customer at about $61.00. The retail service customer at the dealer may pay $59.17 ($38.46 ⴜ 0.65 ⴝ $59.17).

NEW VERSUS REMANUFACTURED PARTS

New parts are manufactured from raw materials and have never been used on a vehicle. A remanufactured component (also called rebuilt) has been used on a vehicle until the component wore out or failed. A remanufacturer totally disassembles the component, cleans, machines, and performs all the necessary steps to restore the part to a “like new” look and function. If properly remanufactured, the component can be expected to deliver the same length of service as a new component part. The cost of a remanufactured component is often less than the cost of a new part. CAUTION: Do not always assume that a remanufactured component is less expensive than a new component. Due to the three-step distribution process, the final cost to the end user (you) may be close to the same!

USED PARTS

Used parts offer another alternative to either new or remanufactured parts. The cost of a used component is typically onehalf the cost of the component if purchased new. Wrecking and salvage yards use a Hollander manual that lists original equipment part numbers and cost and cross-references them to other parts that are the same.

NOTE: Some shops have a policy that requires employees to turn the radio off. 13. Keep yourself neatly groomed including: a. Shirttail tucked into pants (unless shirt is designed to be worn outside) b. Daily bathing and use of deodorant c. Clean hair, regular haircuts, and hair tied back if long d. Men: daily shave or keep beard and/or mustache neatly trimmed e. Women: makeup and jewelry kept to a minimum

WORKING WITH A MENTOR A mentor is a person at the job site who helps the beginning service technician, also called the trainee. The word mentor comes from Greek mythology. In Homer’s The Odyssey, Mentor was the faithful companion and friend of Ulysses (Odysseus), the King of Ithaca. Before Ulysses went to the Trojan Wars, he instructed Mentor to stay and take full charge of the royal household. This meant that Mentor had to be father figure, teacher, role model, counselor, trusted advisor, challenger, and encourager to the King’s son in order that he become a wise and good ruler. Therefore, a good definition of a mentor would be, “A highly qualified individual who is entrusted with the protection and development of an inexperienced technician.” A mentor therefore fulfills many roles, such as:

Teacher—helps teach information and procedures

Coach—has trainee practice service procedures

Counselor—concerned about, but not trained to offer advice on personal life decisions.

Advisor—helps with career-type decisions, such as what tools are needed

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Advocate (stands up for the trainee)—represents and helps the trainee’s concerns be expressed to others

Role model—presents a positive role model every day

QUALIFICATIONS OF A GOOD MENTOR

A good mentor should be assigned to a new technician. Qualifications of a good mentor include:

Trade proficiency—The person selected should be a highly skilled technician.

Good coaching/mentoring skills and techniques—The mentor has to have patience and be willing to help the trainee by explaining each step needed to complete a service procedure.

TECH TIP Adhere to the Times When starting a new job at a shop or dealership, be sure to ask about the following: • What time should I arrive at work? This may be different than the scheduled work starting time. For example, the work day could start at 8 a.m. but the shop owner or service manager may want all technicians to arrive and start to get ready to work at 7:50 a.m. • When is break time? Breaks may or may not be regularly scheduled and it is important for the beginning technician to know and adhere to break times. • When is lunch time? In some busy shops, the lunch period is staggered to be sure that some technicians are always available for work. Always be willing to adhere to the requested lunch period.

Leadership/role model—The mentor should take pride in being a professional service technician and have high ethical and professional standards.

Mentoring a trainee can be frustrating for an experienced technician. This occurs because the mentor needs to verify almost everything the trainee does until satisfied that competence has been achieved. Even very basic procedures need to be watched, such as hoisting the vehicle, changing the oil and oil filter, plus many other operations. As a result, the time taken to help the beginning technician will reduce the efficiency, and therefore, the pay of the mentor. However, after several weeks, the trainee can start helping the mentor, thereby increasing efficiency.

TEAMWORK TEAM BUILDING

A team is a group of individuals working together to achieve a common goal. Even shops or service departments that do not use a team system with a group of technicians is still a team. All members of the service department are really part of a team effort working together to achieve efficient vehicle service and customer satisfaction. The key to building a team that works together is selecting employees that are willing to work together. While the shop owner or service manager at a dealership has hiring authority, every technician should consider what is best for the entire group to help increase repeat business and satisfied customers.

focus efforts on improving your personal and professional life. Goals can include: Career, physical, family, education, financial and public service. There are many helpful web sites that can be used to help set and track progress toward achieving goals. The hardest part of any goal is to write it down. Until it is written down, a goal is not real.

BUSINESS MEETINGS

All service technicians attend business (shop) meetings. A good business meeting will have the following features: 1. An agenda (list of topics to be discussed) will be given out or displayed. 2. The meeting should start on time and end on time. 3. If someone is to give a report or be asked to do a project, this topic should be discussed with the designated person before the meeting to avoid that person from being surprised and made to feel uncomfortable. 4. The meeting should be held following the “Robert’s Rule of Order” guidelines. 5. Often meetings include others from inside or outside the company or shop, so try to look your best and smile to make the best impression.

ADVANCEMENT SKILLS The job of a service technician becomes more valuable to the shop or dealership if work can be accomplished quickly and without any mistakes. Therefore, being careful to avoid errors is the first consideration for any service technician. Then, with experience, the speed of accomplishing tasks can and will increase. More than speed is needed to become a master technician. It requires problem solving and critical thinking skills, too. While beginning technicians are usually not required to diagnose problems, troubleshooting skills are very important toward becoming a master technician. Most master technicians follow a plan which includes: 1. Always verify the customer concern. 2. Perform a thorough visual inspection and check for possible causes of the problem, including damage from road debris or accidents. 3. Use a scan tool and check for stored diagnostic trouble codes (DTCs). 4. Check service information for technical service bulletins (TSBs). 5. Check service information and follow all diagnostic trouble charts. 6. Locate and correct the root cause of the problem.

LEADERSHIP ROLES

As a technician gains experience, he or she often asks for guidance, not only for technical answers, but also for how to handle other issues in the shop, such as paperwork, use of aftermarket parts, and other issues. Therefore, the more experience the technician has, the more likely he or she will be placed in a leadership and role model position.

GOAL SETTING AND BUSINESS MEETINGS GOAL SETTING

The wise service technician sets goals to achieve during a career and life. The purpose of goal setting is to

7. Verify the repair and document the work order. The hardest part of the diagnostic process is to locate the root cause of the problem. The process of analyzing and evaluating information and making a conclusion is called critical thinking.

HOUSEKEEPING DUTIES A professional service technician is usually responsible for keeping his or her work area clean and tidy. Good housekeeping includes all of the following:

Clean floor—If coolant or oil is spilled on the floor during a repair procedure, it should be cleaned before starting another job.

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TECH TIP

TECH TIP Keeping “Things” off the Floor

Write It Down

To make cleaning easier and for a more professional shop appearance, keep only those items on the floor that have to be on the floor and find a place off the floor for all other items.

If a technician needs to have another technician finish a repair due to illness or some other reason, be sure to write down exactly what was done and what needs to be done. Verbal communication, while very effective, is often not a good way to explain multiple steps or processes. For example, the other technician could easily forget that the oil had not yet been added to the engine, which could cause a serious problem if the engine were to be started. If in doubt, write it down.

TECH TIP Look at the Shop from a Customer’s Point of View To determine if the shop and other technicians look professional, step outside and enter the shop through the same door as a customer. Now look around. Look at the shop and the other technicians. Does the shop give the appearance of a professional service facility? If not, try to improve the look by asking the shop owner or service manager to do the same thing in an attempt to create a more professional looking shop.

Tool box—Keep work area and tool box clean and organized.

Items kept off the floor—It is easy to allow parts and other items to be stored in and around the toolbox and in corners. However, having items on the floor makes keeping the area clean and neat looking very difficult.

Keep areas around exits and fire extinguishers clear. Do not store or place parts, boxes, or shop equipment, such as floor jacks and testers, near exits and fire extinguishers. This helps ensure that people can have easy access to exits or the fire extinguishers in the event of an emergency. Avoid spraying chemicals in the air. To help keep the air in the shop clean, keep the use of spray chemicals, such as brake cleaner, to a minimum and avoid spraying where it could result in affecting the air others breathe.

SELF-MANAGEMENT A professional service technician should try to maintain a professional appearance at all times. For example, if coolant or automatic transmission fluid (ATF) gets onto a shirt or pants, the wise technician would change into a clean uniform before working on another vehicle. Many shop owners and service managers recommend that shirttails always be tucked into pants to ensure a more professional appearance.

JOB EVALUATION In most jobs, there is an evaluation of performance. A beginning technician is not expected to perform at the same level as an experienced master technician but should be able to do the following:

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Follow instructions. The trainee should follow the instructions of the mentor or service manager. This includes making

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TECH TIP Don’t Cover Up Mistakes Everyone makes mistakes. While a damaged component or vehicle is never a good thing to have happen, the wise technician should notify the service manager or other person in charge as soon as a problem or accident occurs. Only then can work begin to correct the problem. If a mistake is hidden, eventually someone will learn about the error and then people will not think it was wise to ignore or to cover up the situation.

sure that the person is notified when the job has been completed and if there were any problems.

Do no harm. Avoid exerting a lot of force to door panels or other components to help avoid breaking clips or components. Always use the right tool for the job. For example, never use pliers to remove a bolt or nut, which could round off the flats of the fastener. Always think before acting, “Am I going to hurt something by doing this?”

Keep a neat and clean appearance. It is normal to get dirty while performing service work on a vehicle. However, after each job is completed or even during the repair, try to keep as clean as possible.

Ask that your work be checked. Even though the trainee thinks that the service or repair was done correctly, until confidence has been established, it is wise to ask to have all work double-checked.

CAUTION: Never allow a mistake to reach the customer. It is only a problem if it cannot be corrected.

FORMAL EVALUATION

The mentor and/or service manager may or may not conduct a written evaluation on a regular basis. If a written evaluation is performed, this is called a formal evaluation. A formal evaluation usually includes many points of discussion. See the sample evaluation form.

INFORMAL EVALUATION In many cases, a beginning technician’s activities are simply observed and noted, which is a type of informal evaluation. Both are usually done and both can influence the technician’s pay. NOTE: Most employees are fired from a job as the result of not being able to get along with others, rather than a lack of technical skills.

Technician Evaluation Please check one of the spaces to the left of each characteristic which best expresses your judgment of the technician: ATTITUDE-APPLICATION TO WORK _____outstanding in enthusiasm _____very interested and industrious _____average in diligence and interest _____somewhat indifferent _____definitely not interested

INITIATIVE _____proceeds well on his or her own _____proceeds independently at times _____does all assigned work _____hesitates _____must be pushed frequently

REVIEW QUESTIONS 1. What factors are part of being a professional service technician?

5. A formal evaluation could include what items?

2. What is a mentor?

6. What are the three Cs?

3. What are the roles of a mentor?

7. What should be included on the work order after the repair has been completed?

4. What are the responsibilities the beginning technician has to the shop and/or mentor?

CHAPTER QUIZ 1. Professionalism includes which factor? a. Keeping your word b. Becoming a teammate with your co-workers c. Apologizing if you are wrong d. All of the above

2. Type of communications include ________. a. Verbal b. Written c. Nonverbal d. All of the above

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3. The three Cs include ________, ________, and ________. a. Correction, correct torque, and customer name b. Concern, cause, and correction c. Cause, cost, and caller name d. Captured data, cause, and cost (of the repair)

7. If running late, the wise technician should ________. a. Call the shop and let them know you will be late b. Speed up c. Call the shop and take the day off d. Stop and eat a good breakfast before going to the shop

4. When documenting the work order, what things should be listed? a. The test equipment used in the diagnosis b. The test procedure that was followed c. The parts that were replaced d. All of the above

8. Flat-rate pay means ________. a. The same pay (flat-rate) every week b. The same number of hours every week c. The technician is paid according to the job, not by the number of hours worked d. The technician is paid overtime

5. Technician A says that customer-pay rate is sometimes higher than the factory flat-rate. Technician B says that the factory flat-rate times are usually longer (given more time) compared to aftermarket flat-rate time guides. Which technician is correct? a. Technician A only b. Technician B only c. Both Technicians A and B d. Neither Technician A nor B 6. Housekeeping duties of a technician can include _________. a. Cleaning the floor b. Keeping the work area clean and organized c. Keeping items off the floor whenever possible d. All of the above

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9. Customer pay (CP) means ________. a. Customer pays for the repair or service b. Warranty does not pay for the repair or service c. The technician often gets paid more for each job d. All of the above 10. A mentor performs all of the following except ________. a. Helps guide diagnosis of a problem b. Signs paychecks c. Offers advice on how to do a job d. Advises on professional behavior

WHAT AREAS OF VEHICLE SERVICE ARE COVERED BY THE ASE TESTS? Automobile test service areas include: A1 Engine Repair A2 Automatic Transmission/Transaxle

Even though individual franchises and companies often certify their own technicians, there is a nationally recognized certificate organization, the National Institute for Automotive Service Excellence, better known by its abbreviation, ASE. SEE FIGURE 5–1. ASE is a nonprofit association founded in 1972, and its main goal is to improve the quality of vehicle service through standardized testing and volunteer certification.

for certification, except as noted below. If you have not previously provided work experience information, you will receive a Work Experience Report Form with your admission ticket. You must complete and return this form to receive a certificate. SUBSTITUTIONS FOR WORK EXPERIENCE. You may receive credit for up to one year of the two-year work experience requirement by substituting relevant formal training in one, or a combination, of the following: High School Training: Three full years of training, either in automobile/truck/school bus repair or in collision repair, refinishing, or damage estimating, may be substituted for one year of work experience. Post-High School Training: Two full years of post-high school training in a public or private trade school, technical institute, community or four-year college, or in an apprenticeship program may be counted as one year of work experience. Short Courses: For shorter periods of post-high school training, you may substitute two months of training for one month of work experience. You may receive full credit for the two-year work experience requirement with the following: Completion of Apprenticeship: Satisfactory completion of either a three- or four-year bona fide apprenticeship program.

ARE THERE ANY HANDS-ON ACTIVITIES ON THE ASE TEST?

FIGURE 5–1 The ASE logo. (Courtesy of ASE) If a technician takes and passes all eight of the automobile tests and has achieved two or more years of work experience, ASE will award the designation of ASE Certified Master Automobile Technician. Contact ASE for other certification areas.

HOW CAN I CONTACT ASE? ASE

Toll-free: 1-877-ASE-TECH (273-8324)

101 Blue Seal Drive, SE

1-703-669-6600

Suite 101

Web site: www.ase.com

Leesburg, VA 20175

No. All ASE tests are written using objective-type questions, meaning that you must select the correct answer from four possible alternatives.

WHO WRITES THE ASE QUESTIONS?

All ASE test questions are written by a panel of industry experts, educators, and experienced ASE certified service technicians. Each question is reviewed by the committee and it is checked for the following:

Technically accurate. All test questions use the correct terms and only test for vehicle manufacturer’s recommended service procedures. Slang is not used nor are any aftermarket accessories included on the ASE test.

Manufacturer neutral. All efforts are made to avoid using vehicle or procedures that are manufacturer specific such as to General Motors vehicles or to Toyotas. A service technician should feel comfortable about being able to answer the questions regardless of the type or brand of vehicle.

Logical answers. All effort is made to be sure that all answers (not just the correct answers) are possible. While this may seem to make the test tricky, it is designed to test for real knowledge of the subject.

Random answer. All efforts are made to be sure that the correct answers are not always the longest answer or that one letter, such as c, is not used more than any other letter.

Experience-based questions. The questions asked are generally not knowledge-based questions, but rather require experience to answer correctly. Specifications are not asked for, but instead a question as to what would most likely occur if the unit is out-of-specifications could be asked.

WHEN ARE THE TESTS GIVEN AND WHERE?

The ASE written tests are given at hundreds of test sites throughout the year for online testing. NOTE: ASE also offers tests at other times of the year electronically. Go to the ASE Web site for details. Deadline for registration is usually in late March for the May tests and in late September for the November tests. Consult the ASE registration booklet or Web site for details and locations of the test sites.

WHAT DO I HAVE TO DO TO REGISTER?

You can register

for the ASE tests in three ways: 1. Mail in the registration form that is in the registration booklet. 2. Register online at www.ase.com 3. Telephone at (866) 427-3273 Call ASE toll-free at 1-888-ASE-TEST or visit the Web site for details about cost and dates.

HOW MANY YEARS OF WORK EXPERIENCE ARE NEEDED? ASE requires that you have two or more years of full-time, hands-on working experience either as an automobile, truck, truck equipment, or school bus technician, engine machinist, or in collision repair, refinishing, or damage analysis and estimating

KEY AND DISTRACTER

The key is the correct answer. As part of the test writing sessions, the committee is asked to create other answers which sound feasible but are not correct. These incorrect answers are called distracters.

WHAT TYPES OF QUESTIONS ARE ASKED ON THE ASE TEST? All ASE test questions are objective. This means that there will not be questions where you will have to write an answer.

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Instead, all you have to do is select one of the four possible answers and place a mark in the correct place on the score sheet.

Multiple-choice questions. This type of question has one correct (or mostly correct) answer (called the key) and three incorrect answers. A multiple-choice question example: What part of an automotive engine does not move? a. b. c. d.

Example: Two technicians are discussing an engine that has lower than specified fuel pressure. Technician A says that the fuel pump could be the cause. Technician B says that the fuel pressure regulator could be the cause. Which technician is correct? a. Technician A only b. Technician B only c. Both Technicians A and B d. Neither Technician A nor B

Analysis: Is Technician A correct? The answer is yes because if the fuel pump was defective, the pump pressure could be lower than specified by the vehicle manufacturer. Is Technician B correct? The answer is yes because a stuck open regulator with a weak spring could be the cause of lower than specified fuel pressure. The correct answer is therefore c (Both Technicians A and B are correct).

Most-likely-type questions. This type of question asks which of the four possible items listed is the most likely to cause the problem or symptom. This type of question is often considered to be difficult because recent experience may lead you to answer the question incorrectly because even though it is possible, it is not the “most likely.” Example: Which of the items below is the most likely to cause blue exhaust at engine start? a. Valve stem seals b. Piston rings

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Except-type questions. ASE will sometimes use a question that includes answers that are all correct except one. You have to determine which of the four answers is not correct. Example: A radiator is being pressure tested using a hand-operated tester. This test will check for leaks in all except:

a. Radiator b. Heater core

Technician A only Technician B only Both Technicians A and B Neither Technician A nor B

The best way to answer this type of question is to carefully read the question and consider Technician A and Technician B answers to be solutions to a true or false question. If Technician A is correct, mark on the test by Technician A the letter T for true. (Yes, you can write on the test.) If Technician B is also correct, write the letter T for true by Technician B. Then mark c on your test score sheet, for both technicians are correct.

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The correct answer is a because valve stem seals are the most likely to cause this problem. Answer b is not correct because even though worn piston rings can cause the engine to burn oil and produce blue exhaust smoke, it is not the most likely cause of blue smoke at engine start. Answers c and d are not correct because even though these items could contribute to the engine burning oil and producing blue exhaust smoke, they are not the most likely.

Technician A and Technician B questions. This type of question is generally considered to be the most difficult according to service technicians who take the ASE test. A situation or condition is usually stated and two technicians (A and B) say what they think could be the correct answer and you must decide which technician is correct. a. b. c. d.

Analysis:

Piston Connecting rod Block Valve

The correct answer is c (block). This type of question asks for a specific answer. Answer a (piston), b (connecting rod), and d (valve) all move during normal engine operation. The best answer is c (block) because even though it may vibrate, it does not move as the other parts do.

c. Clogged PCV valve d. A stuck oil pump regulator valve

c. Water pump d. Evaporator

Analysis: The correct answer is d because the evaporator is not included in the cooling system and will not be pressurized during this test. Answers a (radiator), b (heater core), and c (water pump) are all being tested under pressure exerted on the cooling system by the pressure tester.

Least-likely-type questions. Another type of question asked on many ASE tests is a question that asks which of the following is least likely to be the cause of a problem or symptom. In other words, all of the answers are possible, but it is up to the reader to determine which answer is the least likely to be correct. Example: Which of the following is the least likely cause of low oil pressure?

a. Clogged oil pump screen b. Worn main bearing

c. Worn camshaft bearing d. Worn oil pump

Analysis: The correct answer is c because even though worn camshaft bearings can cause low oil pressure, the other answers are more likely to be the cause.

QUESTIONS OFTEN ASKED SHOULD I GUESS IF I DON’T KNOW THE ANSWER? Yes. ASE tests simply record the correct answers, and by guessing, you will have at least a 25% (1 out of 4) chance. If you leave the answer blank, it will be scored as being incorrect. Instead of guessing entirely, try to eliminate as many of the answers as possible as not being very likely. If you can eliminate two out of the four, you have increased your chance of guessing to 50% (two out of four). IS EACH TEST THE SAME EVERY TIME I TAKE IT?

No. ASE writes many questions for each area and selects from this “test bank” for each test session. You may see some of the same questions if you take the same test in the spring and then again in the fall, but you will also see many different questions.

TECH TIP Never Change an Answer Some research has shown that your first answer is most likely to be correct. It is human nature to read too much into the question rather than accept the question as it was written.

CAN I SKIP QUESTIONS I DON’T KNOW AND COME BACK TO ANSWER LATER? Yes. You may skip a question if you wish, but be sure to mark the question and return to answer the question later. It is often recommended to answer the question or guess and go on with the test so that you do not run out of time to go back over the questions.

one or more ASE tests. Therefore, it is wise to take as many tests as you can at each test session.

WILL I RECEIVE NOTICE OF WHICH QUESTIONS I MISSED? ASE sends out a summary of your test results, which shows how many questions you missed in each category, but not individual questions.

WILL ASE SEND ME THE CORRECT ANSWERS TO THE QUESTIONS I MISSED SO I WILL KNOW HOW TO ANSWER THEM IN THE FUTURE? No. ASE will not send you the answers to test questions.

TEST-TAKING TIPS HOW MUCH TIME DO I HAVE TO TAKE THE TESTS?

Each computer-based test will allow enough time for completion, usually between one and two hours for each test. The time allowed for each test is available on the ASE web site.

WILL I HAVE TO KNOW SPECIFICATIONS AND GAUGE READINGS? Yes and no. You will be asked the correct range for a particular component or operation and you must know about what the specification should be. Otherwise, the questions will state that the value is less than or greater than the allowable specification. The question will deal with how the service technician should proceed or what action should be taken.

CAN I TAKE A BREAK DURING THE TEST? Yes, you may use the restroom after receiving permission from the proctor of the test site. CAN I LEAVE EARLY IF I HAVE COMPLETED THE TEST(S)? Yes, you may leave quietly after you have completed the test(s). You must return the score sheet(s) and the test booklets as you leave.

HOW ARE THE TESTS SCORED?

The ASE tests are machine scored and the results tabulated by American College Testing (ACT).

WHAT PERCENTAGE DO I NEED TO ACHIEVE TO PASS THE ASE TEST? While there is no exact number of questions that must be answered correctly in each area, an analysis of the test results indicate that the percentage needed to pass varies from 61% to 69%. Therefore, in order to pass the Engine Repair (A1) ASE certification test, you will have to answer about 39 questions correct out of 60. In other words, you can miss about 21 questions and still pass.

WHAT HAPPENS IF I DO NOT PASS? DO I HAVE TO WAIT A YEAR BEFORE TRYING AGAIN? No. If you fail to achieve a passing score on any ASE test, you can take the test again at the next testing session (in May or November).

DO I HAVE TO PAY ANOTHER REGISTRATION FEE IF I ALREADY PAID IT ONCE? Yes. The registration fee is due at every test session in May or November whether you select to take

START NOW Even if you have been working on vehicles for a long time, taking an ASE certification test can be difficult. The questions will not include how things work or other “textbook” knowledge. The questions are based on “real-world” diagnosis and service. The tests may seem tricky to some because the wrong answers are designed to be similar to the correct answer. If this is your first time taking the test or you are going to recertify, start now to prepare. Allocate time each day to study. PRACTICE IS IMPORTANT Many service technicians do not like taking tests. As a result, many technicians rush through the test to get the pain over with quickly. Also, many service technicians have lots of experience on many different vehicles. This is what makes them good at what they do, but when an everyday problem is put into a question format (multiple choice), the answer may not be as clear as your experience has taught you. KEYS TO SUCCESS

The keys to successful test taking include:

Practice answering similar-type questions.

Carefully read each question two times to make sure you understand the question.

Read each answer.

Pick the best answer.

Avoid reading too much into each question.

Do not change an answer unless you are sure that the answer is definitely wrong.

Look over the glossary of automotive terms for words that are not familiar to you.

The best preparation is practice, practice, and more practice. This is where using the ASE Test Prep practice tests can help.

PREPARE MENTALLY

Practicing also helps relieve another potential problem many people have called “chronic test syndrome.” This condition is basically an inability to concentrate or focus during a test. The slightest noise, fear of failure, and worries about other things all contribute. The best medicine is practice, practice, and more practice. With practice, test taking becomes almost second nature.

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PREPARE PHYSICALLY

Be prepared physically. Get enough

2. Automatic Transmission/Transaxles (A2) ASE Task List

sleep and eat right. Content Area

ONE MONTH BEFORE THE TEST

Budget your time for studying. On average you will need four to six hours of study for each test that you are taking.

Use the ASE Test Prep Online test preparation service three or more times a week for your practice.

Study with a friend or a group if possible.

THE WEEK BEFORE THE TEST

Studying should consist of about two hours of reviewing for each test being taken.

Make sure you know how to get to the testing center. If possible drive to the test site and locate the room.

Get plenty of rest.

Study time is over.

Keep your work schedule light or get the day off if possible.

Eat a small, light meal the evening of the test.

Drink a large glass of water one to two hours before the test. (The brain and body work on electrical impulses, and water is used as a conductor.)

To become certified by ASE, the service technician must have two years of experience and pass a test in each area. If a technician passes all eight automotive certification tests, then the technician is considered a master certified automobile service technician. Tests are administered twice a year, in May and again in November. Registration and payment are required to be sent in early April for the May test and in early October for the November test. Test results are mailed to your home or work address about six to eight weeks after the test(s) is taken.

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CANADA’S AUTOMOTIVE APPRENTICESHIP PROGRAM (RED SEAL) In Canada, in all provinces and territories but Quebec and British Columbia, an Inter-Provincial (IP) Certificate is required. An apprenticeship program is in place that takes a minimum of four years, combining ten months in a shop and about two months in school training in each of the four years. Most apprentices must undergo 7200 hours of training before they can complete the IP examination. ASE certifications are currently used on a voluntary basis since 1993, however an IP Certificate is still required. Other licensing of automotive technicians may be required in some cases, such as environmental substances, liquefied petroleum gas, or steam operators.

RE-CERTIFICATION All ASE certifications expire after five years and the technician needs to take a recertification test to remain certified. As vehicles and technology change, it is important that all technicians attend update classes. Most experts recommend that each technician should have at least 40 hours (one full week) of update training every year. Update training classes can be found through many sources, including: 1. Many parts stores and warehouse distributors provide training classes throughout the year. 2. State or regional associations, such as the Automotive Service Association (www.asashop.org), offer update conferences. 3. Local colleges or training companies offer update training. Other training can be found listed on the International Automotive Technicians Network (www.iatn.net).

NOTE: A valid driver’s license is a must for any automotive service technician.

REVIEW QUESTIONS 1. What are the eight ASE test areas? 2. When are the written ASE tests given?

4. What can a technician do to help prepare to take the certification tests?

3. What types of questions are asked on the ASE certification tests?

CHAPTER QUIZ 1. Which ASE certification test would cover experience in reading an electrical schematic? a. A6 b. A7 c. A8 d. All of the above are possible 2. How many ASE tests must be passed to become a master automotive technician? a. 8 b. 6 c. 4 d. 2 3. How many years of experience are required to achieve ASE certification? a. 8 c. 4 b. 6 d. 2 4. Credit for how many years of work experience can be substituted by attending automotive service training? a. None—no substitution for work experience is permitted b. 1 year c. 2 years d. 3 years 5. When taking an ASE certification test, ________. a. You can write on the test itself if you wish b. No marks are allowed on the test c. Only one test can be taken d. Some hands-on activities may be required

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6. A type of test question not asked on the ASE certification test is ________. a. Most likely c. Fill in the blank b. Least likely d. Multiple choice 7. Which type of question is the same as two true-and-false-type questions? a. All except type b. Technician A and Technician B c. Least likely type d. Most likely type 8. Technician A says that you should guess if you do not know the correct answer. Technician B says that ASE will send you the correct answers to the questions you missed with your test results. Which technician is correct? a. Technician A only b. Technician B only c. Both Technicians A and B d. Neither Technician A nor B 9. The written ASE tests are given every ________. a. January and June c. February and September b. May and November d. March and October 10. A technician should do all of the following to prepare to take the ASE certification test except ________. a. Get a good night’s sleep the night before the test b. Try to keep work schedule light the day of the test c. Eat a big meal d. Have photo ID and entry ticket

PERSONAL PROTECTIVE EQUIPMENT Safety is not just a buzzword on a poster in the work area. Safe work habits can reduce accidents and injuries, ease the workload, and keep employees pain free.

SAFETY GLASSES The most important personal protective equipment (PPE) a technician should wear all the time are safety glasses, which meet standard ANSI Z87.1. SEE FIGURE 6–1. STEEL-TOED SHOES

Steel-toed safety shoes are also a good investment. SEE FIGURE 6–2. If safety shoes are not available, then leather-topped shoes offer more protection than canvas or cloth covered shoes.

GLOVES

Wear gloves to protect your hands from rough or sharp surfaces. Thin rubber gloves are recommended when working around automotive liquids such as engine oil, antifreeze, transmission fluid, or any other liquids that may be hazardous. Several types of gloves and their characteristics include:

FIGURE 6–1 Safety glasses should be worn at all times when working on or around any vehicle or servicing any component.

Latex surgical gloves. These gloves are relatively inexpensive, but tend to stretch, swell, and weaken when exposed to gas, oil, or solvents.

Vinyl gloves. These gloves are also inexpensive and are not affected by gas, oil, or solvents. SEE FIGURE 6–3.

Polyurethane gloves. These gloves are more expensive, yet very strong. Even though these gloves are also not affected by gas, oil, or solvents, they tend to be slippery.

Nitrile gloves. These gloves are exactly like latex gloves, but are not affected by gas, oil, or solvents, yet they tend to be expensive.

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FIGURE 6–2 Steel-toed shoes are a worthwhile investment to help prevent foot injury due to falling objects. Even these well-worn shoes can protect the feet of this service technician.

FIGURE 6–4 One version of a bump cap is this padded plastic insert that is worn inside a regular cloth cap.

FIGURE 6–5 Remove all jewelry before performing service work on any vehicle. FIGURE 6–3 Protective gloves such as these vinyl gloves are available in several sizes. Select the size that allows the gloves to fit snugly. Vinyl gloves last a long time and often can be worn all day to help protect your hands from dirt and possible hazardous materials.

TECH TIP Professional Behavior in the Shop Is a Must To be respected as a professional service technician and for safety, always behave in a professional manner. These behaviors include, but are not limited to the following:

Mechanic’s gloves. These gloves are usually made of synthetic leather and spandex and provide thermo protection, as well as protection from dirt and grime.

• Show respect to other technicians and employees. For example, the shop owner or service manager may not always be right, but they are always the boss. • Avoid horseplay or practical jokes. • Act as if a customer is observing your behavior at all times because this is often the case.

BUMP CAP

Service technicians working under a vehicle should wear a bump cap to protect the head against under-vehicle objects and the pads of the lift. SEE FIGURE 6–4.

HANDS, JEWELRY, AND CLOTHING

Remove jewelry that may get caught on something or act as a conductor to an exposed electrical circuit. SEE FIGURE 6–5. Take care of your hands. Keep your hands clean by washing with soap and hot water that is at least 110°F (43°C). Avoid loose or dangling clothing. Also, ear protection should be worn if the sound around you requires that you raise your voice (sound level higher than 90 decibels [dB]). NOTE: A typical lawnmower produces noise at a level of about 110 dB. This means that everyone who uses a lawnmower or other lawn or garden equipment should wear ear protection.

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SAFETY TIPS FOR TECHNICIANS

When lifting any object, get a secure grip with solid footing. Keep the load close to your body to minimize the strain. Lift with your legs and arms, not your back.

FIGURE 6–8 An electric pusher used to push vehicles into or around the shop. FIGURE 6–6 Always connect an exhaust hose to the tailpipe of the engine of a vehicle to be run inside a building.

FIGURE 6–9 All oily shop cloths should be stored in a metal container equipped with a lid to help prevent spontaneous combustion. FIGURE 6–7 A magnetic tray is a helpful item to keep tools needed up where they can be easily reached without having to bend over saving time and energy over the course of a long day in the shop.

SAFETY TIP Shop Cloth Disposal Always dispose of oily shop cloths in an enclosed container to prevent a fire. SEE FIGURE 6–9. Whenever oily cloths are thrown together on the floor or workbench, a chemical reaction can occur which can ignite the cloth even without an open flame. This process of ignition without an open flame is called spontaneous combustion.

Do not twist your body when carrying a load. Instead, pivot your feet to help prevent strain on the spine.

Ask for help when moving or lifting heavy objects.

Push a heavy object rather than pull it. (This is opposite to the way you should work with tools—never push a wrench! If you do and a bolt or nut loosens, your entire weight is used to propel your hand(s) forward. This usually results in cuts, bruises, or other painful injury.)

Always connect an exhaust hose to the tailpipe of any running vehicle to help prevent the buildup of carbon dioxide (CO) inside a closed garage space. SEE FIGURE 6–6.

When standing, keep objects, parts, and tools with which you are working between chest height and waist height. If seated, work at tasks that are at elbow height. SEE FIGURE 6–7.

There are four basic types of cleaning methods and processes used in vehicle service.

Always be sure the hood is securely held open.

Ask for help when pushing a vehicle or use a motorized pusher. SEE FIGURE 6–8.

POWER WASHING Power washing uses an electric- or gasoline-powered compressor to increase the pressure of water and force it out of a nozzle. The pressure of the water itself is usually

CLEANING METHODS AND PROCESSES

S H OP S A F ET Y

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TO STARTER MOTOR

TO STARTER MOTOR

STEP 2

STEP 1

STALLED VEHICLE

STARTING VEHICLE

TO ENGINE GROUND

TO ENGINE GROUND

STEP 3 STEP 4

ENGINE BLOCK OR METAL BRACKET ON ENGINE BLOCK

FIGURE 6–10 Jumper cable usage guide.

ABRASIVE CLEANING

TECH TIP Pound with Something Softer If you must pound on something, be sure to use a tool that is softer than what you are about to pound on to avoid damage. Examples are given in the following table. The Material Being Pounded

What to Pound With

Steel or cast iron

Brass or aluminum hammer or punch

Aluminum

Plastic or rawhide mallet or plastic-covered dead-blow hammer

Plastic

Rawhide mallet or plastic dead-blow hammer

enough to remove dirt, grease, and grime from vehicle components. Sometimes a chemical cleaner, such as a detergent, is added to the water to help with cleaning. SAFE USE OF POWER WASHERS. Because water is being sprayed at high pressure, a face shield should be worn when using a power washer to protect not only the eyes but also the face in the event of the spray being splashed back toward the technician. Also use a pressure washer in an area where the runoff from the cleaning will not contaminate local groundwater or cause harm to plants or animals.

Abrasive cleaning is used to clean disassembled parts, such as engine blocks. The abrasives used include steel shot, ground walnut shells, or in the case of cleaning paint from a vehicle body, baking soda can be used. SAFE USE OF ABRASIVE CLEANERS. Always wear a protective face shield and protective clothing, including gloves, long sleeves, and long pants.

THERMAL OVENS

Thermal cleaning uses heat to bake off grease and dirt with special high-temperature ovens. This method of cleaning requires the use of expensive equipment but does not use any hazardous chemicals and is environmentally safe. SAFE USE OF THERMAL OVENS. Because thermal ovens operate at high temperatures, often exceeding 600°F (315°C), the oven should be turned off and allowed to cool overnight before removing the parts from the oven to avoid being exposed to the high temperature.

ELECTRICAL CORD SAFETY Use correctly grounded three-prong sockets and extension cords to operate power tools. Some tools use only two-prong plugs. Make sure these are double insulated and repair or replace any electrical cords that are cut or damaged to prevent the possibility of an electrical shock. When not in use, keep electrical cords off the floor to prevent tripping over them. Tape the cords down if they are placed in high foot traffic areas.

CHEMICAL/MICROBE CLEANING

Chemical cleaning involves one of several cleaning solutions, including detergent, solvents, or small, living microorganisms called microbes that eat oil and grease. The microbes live in water and eat the hydrocarbons that are the basis of grease and oil. SAFE USE OF CHEMICAL CLEANING. A face shield should be worn when cleaning parts using a chemical cleaner. Avoid spilling the cleaner on the floor to help prevent slipping accidents. Clean and replace the chemical cleaner regularly.

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JUMP-STARTING AND BATTERY SAFETY To jump-start another vehicle with a dead battery, connect goodquality copper jumper cables as indicated in FIGURE 6–10 or use a jump box. The last connection made should always be on the

FIGURE 6–11 The air pressure going to the nozzle should be reduced to 30 PSI or less.

FIGURE 6–12 A typical fire extinguisher designed to be used on type class A, B, or C fires.

SAFETY TIP Compressed Air Safety Improper use of an air nozzle can cause blindness or deafness. Compressed air must be reduced to less than 30 PSI (206 kPa). SEE FIGURE 6–11. If an air nozzle is used to dry and clean parts, make sure the air stream is directed away from anyone else in the immediate area. Always use an OSHA-approved nozzle with side slits that limit the maximum pressure at the nozzle to 30 PSI. Coil and store air hoses when they are not in use.

engine block or an engine bracket as far from the battery as possible. It is normal for a spark to be created when the jumper cables finally complete the jumper cable connections, and this spark could cause an explosion of the gases around the battery. Many newer vehicles have special ground connections built away from the battery just for the purpose of jump-starting. Check the owner manual or service information for the exact location. Batteries contain acid and should be handled with care to avoid tipping them greater than a 45-degree angle. Always remove jewelry when working around a battery to avoid the possibility of electrical shock or burns, which can occur when the metal comes in contact with a 12 volt circuit and ground, such as the body of the vehicle.

FIGURE 6–13 A CO2 fire extinguisher being used on a fire set in an open steel drum during a demonstration at a fire department training center.

Class D is effective only on combustible metals such as powdered aluminum, sodium, or magnesium.

The class rating is clearly marked on the side of every fire extinguisher. Many extinguishers are good for multiple types of fires. SEE FIGURE 6–12. When using a fire extinguisher, remember the word “PASS.” P Pull the safety pin.

FIRE EXTINGUISHERS CLASSES OF FIRE EXTINGUISHERS

There are four classes of fire extinguishers. Each class should be used on specific fires only.

Class A is designed for use on general combustibles, such as cloth, paper, and wood. Class B is designed for use on flammable liquids and greases, including gasoline, oil, thinners, and solvents. Class C is used only on electrical fires.

A Aim the nozzle of the extinguisher at the base of the fire. S Squeeze the lever to actuate the extinguisher. S Sweep the nozzle from side to side.

SEE FIGURE 6–13.

TYPES OF FIRE EXTINGUISHERS

Types of fire extinguish-

ers include the following:

Water. A water fire extinguisher, usually in a pressurized container, is good to use on Class A fires by reducing the temperature to the point where a fire cannot be sustained.

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FIGURE 6–14 A treated wool blanket is kept in this easy-to-open wall-mounted holder and should be placed in a centralized location in the shop.

Carbon dioxide (CO2). A carbon dioxide fire extinguisher is good for almost any type of fire, especially Class B or Class C materials. A CO2 fire extinguisher works by removing the oxygen from the fire and the cold CO2 also helps reduce the temperature of the fire.

Dry chemical (yellow). A dry chemical fire extinguisher is good for Class A, B, or C fires by coating the flammable materials, which eliminates the oxygen from the fire. A dry chemical fire extinguisher tends to be very corrosive and will cause damage to electronic devices.

FIGURE 6–15 A first aid box should be centrally located in the shop and kept stocked with the recommended supplies.

FIRE BLANKETS Fire blankets are required to be available in the shop areas. If a person is on fire, a fire blanket should be removed from its storage bag and thrown over and around the victim to smother the fire. SEE FIGURE 6–14 showing a typical fire blanket.

FIRST AID AND EYE WASH STATIONS All shop areas must be equipped with a first aid kit and an eye wash station centrally located and kept stocked with emergency supplies.

FIRST AID KIT

A first aid kit should include:

Bandages (variety)

Gauze pads

Roll gauze

Iodine swab sticks

Antibiotic ointment

Hydrocortisone cream

Burn gel packets

Eye wash solution

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FIGURE 6–16 A typical eye wash station. Often a thorough flushing of the eyes with water is the best treatment in the event of eye contamination.

Scissors

Tweezers

Gloves

First aid guide

SEE FIGURE 6–15. Every shop should have a person trained in first aid. If there is an accident, call for help immediately.

EYE WASH STATION

An eye wash station should be centrally located and used whenever any liquid or chemical gets into the eyes. If such an emergency does occur, keep eyes in a constant stream of water and call for professional assistance. SEE FIGURE 6–16.

TECH TIP Mark Off the Service Area Some shops rope off the service bay area to help keep traffic and distractions to a minimum, which could prevent personal injury. SEE FIGURE 6–17.

FIGURE 6–17 This area has been blocked off to help keep visitors from the dangerous work area.

CHAPTER QUIZ 1. What do you call the service technician’s protective head cover? a. Cap c. Bump cap b. Hat d. Helmet 2. All safety glasses should meet the standards set by ______________. a. ANSI c. ASE b. SAE d. DOT 3. When washing hands, the water should be at what temperature? a. 98°F (37°C) c. 125°F (52°C) b. 110°F (43°C) d. 135°F (57°C) 4. Hearing protection should be worn anytime the noise level exceeds ______________. a. 60 dB c. 80 dB b. 70 dB d. 90 dB 5. Two technicians are discussing the safe use of a wrench. Technician A says that a wrench should be pulled toward you. Technician B says that a wrench should be pushed away from you. Which technician is correct? a. Technician A only b. Technician B only c. Both Technicians A and B d. Neither Technician A nor B

6. Exhaust hoses should be used because one of the exhaust gases is deadly in high concentration. This gas is ______________. a. Carbon monoxide (CO) b. Carbon dioxide (CO2) c. Hydrocarbons (HC) d. Oxides of nitrogen (NOX) 7. The process of combustion occurring without an open flame is called ______________. a. Direct ignition b. Non-open flame combustion c. Spontaneous combustions d. Cold fusion 8. When using a fire extinguisher, what word can be used to remember what to do? a. PASS c. RED b. FIRE d. LEVER 9. Which type of fire extinguisher can create a corrosive compound when discharged? a. CO2 c. Water b. Dry chemical d. CO 10. Which item is usually not included in a first aid kit? a. Eye wash solution c. Fire blanket b. Antibiotic cream d. Bandages

Hazardous waste materials are chemicals, or components, that the shop no longer needs that pose a danger to the environment and people if they are disposed of in ordinary garbage cans or sewers. However, no material is considered hazardous waste until the shop has finished using it and is ready to dispose of it.

monitor, control, and educate workers regarding health and safety in the workplace.

EPA The Environmental Protection Agency (EPA) publishes a list of hazardous materials that is included in the Code of Federal Regulations (CFR). The EPA considers waste hazardous if it is included on the EPA list of hazardous materials, or it has one or more of the following characteristics:

Reactive. Any material that reacts violently with water or other chemicals is considered hazardous.

Corrosive. If a material burns the skin, or dissolves metals and other materials, a technician should consider it hazardous. A pH scale is used, with the number 7 indicating neutral. Pure water has a pH of 7. Lower numbers indicate an acidic solution and higher numbers indicate a caustic solution. If a material releases cyanide gas, hydrogen sulfide gas, or similar gases when exposed to low pH acid solutions, it is considered hazardous.

Toxic. Materials are hazardous if they leak one or more of eight different heavy metals in concentrations greater than 100 times the primary drinking water standard.

Ignitable. A liquid is hazardous if it has a flash point below 140°F (60°C), and a solid is hazardous if it ignites spontaneously.

Radioactive. Any substance that emits measurable levels of radiation is radioactive. When individuals bring containers of a highly radioactive substance into the shop environment, qualified personnel with the appropriate equipment must test them.

PERSONAL PROTECTIVE EQUIPMENT (PPE)

When handling hazardous waste material, one must always wear the proper protective clothing and equipment detailed in the right-to-know laws. This includes respirator equipment. All recommended procedures must be followed accurately. Personal injury may result from improper clothing, equipment, and procedures when handling hazardous materials.

FEDERAL AND STATE LAWS OCCUPATIONAL SAFETY AND HEALTH ACT

The United States Congress passed the Occupational Safety and Health Act (OSHA) in 1970. This legislation was designed to assist and encourage the citizens of the United States in their efforts to assure:

Safe and healthful working conditions by providing research, information, education, and training in the field of occupational safety and health.

Safe and healthful working conditions for working men and women by authorizing enforcement of the standards developed under the Act.

Because about 25% of workers are exposed to health and safety hazards on the job, the OSHA standards are necessary to

hazardous material users are responsible for hazardous materials from the time they become a waste until the proper waste disposal is completed. Many shops hire an independent hazardous waste hauler to dispose of hazardous waste material. The shop owner, or manager, should have a written contract with the hazardous waste hauler. Rather than have hazardous waste material hauled to an approved hazardous waste disposal site, a shop may choose to recycle the material in the shop. Therefore, the user must store hazardous waste material properly and safely, and be responsible for the transportation of this material until it arrives at an approved hazardous waste disposal site, where it can be processed according to the law. The RCRA controls the following types of automotive waste:

FIGURE 7–1 Material safety data sheets (MSDS) should be readily available for use by anyone in the area who may come into contact with hazardous materials.

RIGHT-TO-KNOW LAWS

The right-to-know laws state that employees have a right to know when the materials they use at work are hazardous. The right-to-know laws started with the Hazard Communication Standard published by OSHA in 1983. Originally, this document was intended for chemical companies and manufacturers that required employees to handle hazardous materials in their work situation but the federal courts have decided to apply these laws to all companies, including automotive service shops. Under the right-toknow laws, the employer has responsibilities regarding the handling of hazardous materials by their employees. All employees must be trained about the types of hazardous materials they will encounter in the workplace. The employees must be informed about their rights under legislation regarding the handling of hazardous materials. MATERIAL SAFETY DATA SHEETS (MSDS). All hazardous materials must be properly labeled, and information about each hazardous material must be posted on material safety data sheets (MSDS) available from the manufacturer. In Canada, MSDS information is called Workplace Hazardous Materials Information Systems (WHMIS). The employer has a responsibility to place MSDS information where they are easily accessible by all employees. The MSDS information provide the following information about the hazardous material: chemical name, physical characteristics, protective handling equipment, explosion/fire hazards, incompatible materials, health hazards, medical conditions aggravated by exposure, emergency and first aid procedures, safe handling, and spill/leak procedures. The employer also has a responsibility to make sure that all hazardous materials are properly labeled. The label information must include health, fire, and reactivity hazards posed by the material, as well as the protective equipment necessary to handle the material. The manufacturer must supply all warning and precautionary information about hazardous materials. This information must be read and understood by the employee before handling the material. SEE FIGURE 7–1.

RESOURCE CONSERVATION AND RECOVERY ACT (RCRA) Federal and state laws control the disposal of hazardous waste materials and every shop employee must be familiar with these laws. Hazardous waste disposal laws include the Resource Conservation and Recovery Act (RCRA). This law states that

Paint and body repair products waste

Solvents for parts and equipment cleaning

Batteries and battery acid

Mild acids used for metal cleaning and preparation

Waste oil, and engine coolants or antifreeze

Air-conditioning refrigerants and oils

Engine oil filters

CLEAN AIR ACT

Air-conditioning (A/C) systems and refrigerant are regulated by the Clean Air Act (CAA), Title VI, Section 609. Technician certification and service equipment is also regulated. Any technician working on automotive A/C systems must be certified. A/C refrigerants must not be released or vented into the atmosphere, and used refrigerants must be recovered.

ASBESTOS HAZARDS Friction materials such as brake and clutch linings often contain asbestos. While asbestos has been eliminated from most original equipment friction materials, the automotive service technician cannot know whether the vehicle being serviced is or is not equipped with friction materials containing asbestos. It is important that all friction materials be handled as if they do contain asbestos. Asbestos exposure can cause scar tissue to form in the lungs. This condition is called asbestosis. It gradually causes increasing shortness of breath, and the scarring to the lungs is permanent. Even low exposures to asbestos can cause mesothelioma, a type of fatal cancer of the lining of the chest or abdominal cavity. Asbestos exposure can also increase the risk of lung cancer as well as cancer of the voice box, stomach, and large intestine. It usually takes 15 to 30 years or more for cancer or asbestos lung scarring to show up after exposure. Scientists call this the latency period. Government agencies recommend that asbestos exposure be eliminated or controlled to the lowest level possible. These agencies have developed recommendations and standards that the automotive service technician and equipment manufacturer should follow. These U.S. federal agencies include the National Institute for Occupational Safety and Health (NIOSH), Occupational Safety and Health Administration (OSHA), and Environmental Protection Agency (EPA).

ASBESTOS OSHA STANDARDS The Occupational Safety and Health Administration (OSHA) has established three levels of asbestos exposure. Any vehicle service establishment that does either

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49

brake or clutch work must limit employee exposure to asbestos to less than 0.2 fibers per cubic centimeter (cc) as determined by an air sample. If the level of exposure to employees is greater than specified, corrective measures must be performed and a large fine may be imposed. NOTE: Research has found that worn asbestos fibers such as those from automotive brakes or clutches may not be as hazardous as first believed. Worn asbestos fibers do not have sharp flared ends that can latch onto tissue, but rather are worn down to a dust form that resembles talc. Grinding or sawing operations on unworn brake shoes or clutch discs will contain harmful asbestos fibers. To limit health damage, always use proper handling procedures while working around any component that may contain asbestos.

ASBESTOS EPA REGULATIONS

The federal Environmental Protection Agency (EPA) has established procedures for the removal and disposal of asbestos. The EPA procedures require that products containing asbestos be “wetted” to prevent the asbestos fibers from becoming airborne. According to the EPA, asbestos-containing materials can be disposed of as regular waste. Only when asbestos becomes airborne is it considered to be hazardous.

ASBESTOS HANDLING GUIDELINES

The air in the shop area can be tested by a testing laboratory, but this can be expensive. Tests have determined that asbestos levels can easily be kept below the recommended levels by using a liquid, like water, or a special vacuum. NOTE: The service technician cannot tell whether the old brake pads, shoes, or clutch discs contain asbestos. Therefore, to be safe, the technician should assume that all brake pads, shoes, or clutch discs contain asbestos.

HEPA VACUUM. A special high-efficiency particulate air (HEPA) vacuum system has been proven to be effective in keeping asbestos exposure levels below 0.1 fibers per cubic centimeter. SOLVENT SPRAY. Many technicians use an aerosol can of brake cleaning solvent to wet the brake dust and prevent it from becoming airborne. A solvent is a liquid that is used to dissolve dirt, grime, or solid particles. Commercial brake cleaners are available that use a concentrated cleaner that is mixed with water. SEE FIGURE 7–2. The waste liquid is filtered, and when dry, the filter can be disposed of as solid waste. DISPOSAL OF BRAKE DUST AND BRAKE SHOE. The hazard of asbestos occurs when asbestos fibers are airborne. Once the asbestos has been wetted down, it is then considered to be solid waste, rather than hazardous waste. Old brake shoes and pads should be enclosed, preferably in a plastic bag, to help prevent any of the brake material from becoming airborne. Always follow current federal and local laws concerning disposal of all waste.

WARNING Never use compressed air to blow brake dust. The fine talclike brake dust can create a health hazard even if asbestos is not present or is present in dust rather than fiber form.

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FIGURE 7–2 All brakes should be moistened with water or solvent to help prevent brake dust from becoming airborne.

USED BRAKE FLUID Most brake fluid is made from polyglycol, is water soluble, and can be considered hazardous if it has absorbed metals from the brake system.

STORAGE AND DISPOSAL OF BRAKE FLUID

Collect brake fluid in a container clearly marked to indicate that it is designated for that purpose.

If the waste brake fluid is hazardous, be sure to manage it appropriately and use only an authorized waste receiver for its disposal.

If the waste brake fluid is nonhazardous (such as old, but unused), determine from your local solid waste collection provider what should be done for its proper disposal.

Do not mix brake fluid with used engine oil.

Do not pour brake fluid down drains or onto the ground.

Recycle brake fluid through a registered recycler.

USED OIL Used oil is any petroleum-based or synthetic oil that has been used. During normal use, impurities such as dirt, metal scrapings, water, or chemicals can get mixed in with the oil. Eventually, this used oil must be replaced with virgin or re-refined oil. The EPA’s used oil management standards include a three-pronged approach to determine if a substance meets the definition of used oil. To meet the EPA’s definition of used oil, a substance must meet each of the following three criteria.

Origin. The first criterion for identifying used oil is based on the oil’s origin. Used oil must have been refined from crude oil or made from synthetic materials. Animal and vegetable oils are excluded from the EPA’s definition of used oil.

Use. The second criterion is based on whether and how the oil is used. Oils used as lubricants, hydraulic fluids, heat transfer fluids, and for other similar purposes are considered

NEVER STORE USED OIL IN ANYTHING OTHER THAN TANKS AND STORAGE CONTAINERS. Used oil may also be stored in units that are permitted to store regulated hazardous waste. USED OIL FILTER DISPOSAL REGULATIONS. Used oil filters contain used engine oil that may be hazardous. Before an oil filter is placed into the trash or sent to be recycled, it must be drained using one of the following hot-draining methods approved by the EPA.

FIGURE 7–3 A typical aboveground oil storage tank.

used oil. The EPA’s definition also excludes products used as cleaning agents, as well as certain petroleum-derived products like antifreeze and kerosene.

Contaminants. The third criterion is based on whether the oil is contaminated with either physical or chemical impurities. In other words, to meet the EPA’s definition, used oil must become contaminated as a result of being used. This aspect of the EPA’s definition includes residues and contaminants generated from handling, storing, and processing used oil.

NOTE: The release of only 1 gallon of used oil (a typical oil change) can make 1 million gallons of fresh water undrinkable. If used oil is dumped down the drain and enters a sewage treatment plant, concentrations as small as 50 to 100 parts per million (ppm) in the wastewater can foul sewage treatment processes. Never mix a listed hazardous waste, gasoline, wastewater, halogenated solvent, antifreeze, or an unknown waste material with used oil. Adding any of these substances will cause the used oil to become contaminated, which classifies it as hazardous waste.

STORAGE AND DISPOSAL OF USED OIL Once oil has been used, it can be collected, recycled, and used over and over again. An estimated 380 million gallons of used oil are recycled each year. Recycled used oil can sometimes be used again for the same job or can take on a completely different task. For example, used engine oil can be re-refined and sold at some discount stores as engine oil or processed for furnace fuel oil. After collecting used oil in an appropriate container such as a 55 gallon steel drum, the material must be disposed of in one of two ways.

Shipped offsite for recycling

Burned in an onsite or offsite EPA-approved heater for energy recovery

Used oil must be stored in compliance with an existing underground storage tank (UST) or an aboveground storage tank (AGST) standard, or kept in separate containers. SEE FIGURE 7–3. Containers are portable receptacles, such as a 55 gallon steel drum. KEEP USED OIL STORAGE DRUMS IN GOOD CONDITION. This means that they should be covered, secured from vandals, properly labeled, and maintained in compliance with local fire codes. Frequent inspections for leaks, corrosion, and spillage are an essential part of container maintenance.

Puncture the filter antidrainback valve or filter dome end and hot drain for at least 12 hours

Hot draining and crushing

Dismantling and hot draining

Any other hot-draining method, which will remove all the used oil from the filter

After the oil has been drained from the oil filter, the filter housing can be disposed of in any of the following ways.

Sent for recycling

Picked up by a service contract company

Disposed of in regular trash

SOLVENTS The major sources of chemical danger are liquid and aerosol brake cleaning fluids that contain chlorinated hydrocarbon solvents. Several other chemicals that do not deplete the ozone, such as heptane, hexane, and xylene, are now being used in nonchlorinated brake cleaning solvents. Some manufacturers are also producing solvents they describe as environmentally responsible, which are biodegradable and noncarcinogenic (not cancer causing). There is no specific standard for physical contact with chlorinated hydrocarbon solvents or the chemicals replacing them. All contact should be avoided whenever possible. The law requires an employer to provide appropriate protective equipment and ensure proper work practices by an employee handling these chemicals.

EFFECTS OF CHEMICAL POISONING The effects of exposure to chlorinated hydrocarbon and other types of solvents can take many forms. Short-term exposure at low levels can cause symptoms such as:

Headache

Nausea

Drowsiness

Dizziness

Lack of coordination

Unconsciousness

It may also cause irritation of the eyes, nose, and throat, and flushing of the face and neck. Short-term exposure to higher concentrations can cause liver damage with symptoms such as yellow jaundice or dark urine. Liver damage may not become evident until several weeks after the exposure.

HAZARDOUS SOLVENTS AND REGULATORY STATUS Most solvents are classified as hazardous wastes. Other characteristics of solvents include the following:

Solvents with flash points below 140°F (60°C) are considered flammable and, like gasoline, are federally regulated by the Department of Transportation (DOT).

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FIGURE 7–4 Washing hands and removing jewelry are two important safety habits all service technicians should practice. FIGURE 7–5 Typical fireproof flammable storage cabinet. SAFETY TIP Hand Safety Service technicians should wash their hands with soap and water after handling engine oil, differential oil, or transmission fluids or wear protective rubber gloves. Another safety hint is that the service technician should not wear watches, rings, or other jewelry that could come in contact with electrical or moving parts of a vehicle. SEE FIGURE 7–4.

Solvents and oils with flash points above 60°C are considered combustible and, like engine oil, are also regulated by the DOT. All flammable items must be stored in a fireproof container. SEE FIGURE 7–5.

It is the responsibility of the repair shop to determine if its spent solvent is hazardous waste. Solvent reclaimers are available that clean and restore the solvent so it lasts indefinitely.

USED SOLVENTS Used or spent solvents are liquid materials that have been generated as waste and may contain xylene, methanol, ethyl ether, and methyl isobutyl ketone (MIBK). These materials must be stored in OSHA-approved safety containers with the lids or caps closed tightly. Additional requirements include the following:

Containers should be clearly labeled “Hazardous Waste” and the date the material was first placed into the storage receptacle should be noted.

Labeling is not required for solvents being used in a parts washer.

Used solvents will not be counted toward a facility’s monthly output of hazardous waste if the vendor under contract removes the material.

52

Used solvents may be disposed of by recycling with a local vendor, such as SafetyKleen®, to have the used solvent removed according to specific terms in the vendor agreement. Use aqueous-based (nonsolvent) cleaning systems to help avoid the problems associated with chemical solvents. SEE FIGURE 7–6.

CHAPTER 7

FIGURE 7–6 Using a water-based cleaning system helps reduce the hazards from using strong chemicals.

?

FREQUENTLY ASKED QUESTION

How Can You Tell If a Solvent Is Hazardous? If a solvent or any of the ingredients of a product contains “fluor” or “chlor” then it is likely to be hazardous. Check the instructions on the label for proper use and disposal procedures.

COOLANT DISPOSAL Coolant is a mixture of antifreeze and water. New antifreeze is not considered to be hazardous even though it can cause death if ingested. Used antifreeze may be hazardous due to dissolved metals from the engine and other components of the cooling system. These metals can include iron, steel, aluminum, copper, brass, and lead

FIGURE 7–7 Used antifreeze coolant should be kept separate and stored in a leakproof container until it can be recycled or disposed of according to federal, state, and local laws. Note that the storage barrel is placed inside another container to catch any coolant that may spill out of the inside barrel. (from older radiators and heater cores). Coolant should be disposed of in one of the following ways:

Coolant should be recycled either onsite or offsite.

Used coolant should be stored in a sealed and labeled container. SEE FIGURE 7–7.

Used coolant can often be disposed of into municipal sewers with a permit. Check with local authorities and obtain a permit before discharging used coolant into sanitary sewers.

FIGURE 7–8 This red gasoline container holds about 30 gallons of gasoline and is used to fill vehicles used for training.

plates contain lead, which is highly poisonous. For this reason, disposing of batteries improperly can cause environmental contamination and lead to severe health problems.

BATTERY HANDLING AND STORAGE

LEAD-ACID BATTERY WASTE About 70 million spent lead-acid batteries are generated each year in the United States alone. Lead is classified as a toxic metal and the acid used in lead-acid batteries is highly corrosive. The vast majority (95% to 98%) of these batteries are recycled through lead reclamation operations and secondary lead smelters for use in the manufacture of new batteries.

BATTERY DISPOSAL

Used lead-acid batteries must be reclaimed or recycled in order to be exempt from hazardous waste regulations. Leaking batteries must be stored and transported as hazardous waste. Some states have more strict regulations, which require special handling procedures and transportation. According to the Battery Council International (BCI), battery laws usually include the following rules. 1. Lead-acid battery disposal is prohibited in landfills or incinerators. Batteries are required to be delivered to a battery retailer, wholesaler, recycling center, or lead smelter. 2. All retailers of automotive batteries are required to post a sign that displays the universal recycling symbol and indicates the retailer’s specific requirements for accepting used batteries. 3. Battery electrolyte contains sulfuric acid, which is a very corrosive substance capable of causing serious personal injury, such as skin burns and eye damage. In addition, the battery

Batteries, whether new or used, should be kept indoors if possible. The storage location should be an area specifically designated for battery storage and must be well ventilated (to the outside). If outdoor storage is the only alternative, a sheltered and secured area with acid-resistant secondary containment is strongly recommended. It is also advisable that acid-resistant secondary containment be used for indoor storage. In addition, batteries should be placed on acid-resistant pallets and never stacked.

FUEL SAFETY AND STORAGE Gasoline is a very explosive liquid. The expanding vapors that come from gasoline are extremely dangerous. These vapors are present even in cold temperatures. Vapors formed in gasoline tanks on many vehicles are controlled, but vapors from gasoline storage may escape from the can, resulting in a hazardous situation. Therefore, place gasoline storage containers in a well-ventilated space. Although diesel fuel is not as volatile as gasoline, the same basic rules apply to diesel fuel and gasoline storage. These rules include the following: 1. Use storage cans that have a flash-arresting screen at the outlet. These screens prevent external ignition sources from igniting the gasoline within the can when someone pours the gasoline or diesel fuel. 2. Use only a red approved gasoline container to allow for proper hazardous substance identification. SEE FIGURE 7–8.

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3. Do not fill gasoline containers completely full. Always leave the level of gasoline at least 1 in. from the top of the container. This action allows expansion of the gasoline at higher temperatures. If gasoline containers are completely full, the gasoline will expand when the temperature increases. This expansion forces gasoline from the can and creates a dangerous spill. If gasoline or diesel fuel containers must be stored, place them in a designated storage locker or facility. 4. Never leave gasoline containers open, except while filling or pouring gasoline from the container. 5. Never use gasoline as a cleaning agent. 6. Always connect a ground strap to containers when filling or transferring fuel or other flammable products from one container to another to prevent static electricity that could result in explosion and fire. These ground wires prevent the buildup of a static electric charge, which could result in a spark and disastrous explosion.

AIRBAG HANDLING Airbag modules are pyrotechnic devices that can be ignited if exposed to an electrical charge or if the body of the vehicle is subjected to a shock. Airbag safety should include the following precautions. 1. Disarm the airbag(s) if you will be working in the area where a discharged bag could make contact with any part of your body. Consult service information for the exact procedure to follow for the vehicle being serviced. 2. If disposing of an airbag, the usual procedure is to deploy the airbag using a 12 volt power supply, such as a jump-start box, using long wires to connect to the module to ensure a safe deployment. 3. Do not expose an airbag to extreme heat or fire. 4. Always carry an airbag pointing away from your body. 5. Place an airbag module facing upward.

3. Used tires present a fire hazard and, when burned, create a large amount of black smoke that contaminates the air.

DISPOSAL METHODS

Used tires should be disposed of in one

of the following ways. 1. Used tires can be reused until the end of their useful life. 2. Tires can be retreaded. 3. Tires can be recycled or shredded for use in asphalt. 4. Derimmed tires can be sent to a landfill (most landfill operators will shred the tires because it is illegal in many states to landfill whole tires). 5. Tires can be burned in cement kilns or other power plants where the smoke can be controlled. 6. A registered scrap tire handler should be used to transport tires for disposal or recycling.

AIR-CONDITIONING REFRIGERANT OIL DISPOSAL Air-conditioning refrigerant oil contains dissolved refrigerant and is therefore considered to be hazardous waste. This oil must be kept separated from other waste oil or the entire amount of oil must be treated as hazardous. Used refrigerant oil must be sent to a licensed hazardous waste disposal company for recycling or disposal. SEE FIGURE 7–9.

WASTE CHART

All automotive service facilities create some waste and while most of it is handled properly, it is important that all hazardous and nonhazardous waste be accounted for and properly disposed. SEE CHART 7–1 for a list of typical wastes generated at automotive shops, plus a checklist for keeping track of how these wastes are handled.

6. Always follow the manufacturer’s recommended procedure for airbag disposal or recycling, including the proper packaging to use during shipment. 7. Wear protective gloves if handling a deployed airbag. 8. Always wash your hands or body well if exposed to a deployed airbag. The chemicals involved can cause skin irritation and possible rash development.

USED TIRE DISPOSAL ENVIRONMENTAL CONCERN

Used tires are an environmental concern because of several reasons, including the following: 1. In a landfill, they tend to “float” up through the other trash and rise to the surface. 2. The inside of tires traps and holds rainwater, which is a breeding ground for mosquitoes. Mosquito-borne diseases include encephalitis and dengue fever.

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FIGURE 7–9 Air-conditioning refrigerant oil must be kept separated from other oils because it contains traces of refrigerant and must be treated as hazardous waste.

TECH TIP Remove Components That Contain Mercury Some vehicles have a placard near the driver’s side door that lists the components that contain the heavy metal, mercury. Mercury can be absorbed through the skin and is a heavy metal that once absorbed by the body does not leave. SEE FIGURE 7–10. These components should be removed from the vehicle before the rest of the body is sent to be recycled to help prevent releasing mercury into the environment. FIGURE 7–10 Placard near driver’s door, including what devices in the vehicle contain mercury.

TECH TIP What Every Technician Should Know The Hazardous Materials Identification Guide (HMIG) is the standard labeling for all materials. The service technician should be aware of the meaning of the label. SEE FIGURE 7–11.

6. Used engine oil should be disposed of by all except the following methods. a. Disposed of in regular trash b. Shipped offsite for recycling c. Burned onsite in a waste oil-approved heater d. Burned offsite in a waste oil-approved heater 7. All of the following are the proper ways to dispose of a drained oil filter except ______________. a. Sent for recycling b. Picked up by a service contract company c. Disposed of in regular trash d. Considered to be hazardous waste and disposed of accordingly

FIGURE 8–1 The dimensions of a typical bolt showing where sizes are measured. The major diameter is called the crest.

TORX® BOLT

ALLEN BOLT

CHEESE HEAD SCREW

PAN HEAD SCREW

FIGURE 8–3 Bolts and screws have many different heads which determine what tool must be used. Bolts are identified by their diameter and length as measured from below the head, and not by the size of the head or the size of the wrench used to remove or install the bolt. Bolts and screws have many different-shaped heads. SEE FIGURE 8–3. Fractional thread sizes are specified by the diameter in fractions of an inch and the number of threads per inch. Typical UNC thread sizes would be 5/16-18 and 1/2-13. Similar UNF thread sizes would be 5/16-24 and1/2-20. SEE CHART 8–1.

METRIC BOLTS FIGURE 8–2 Thread pitch gauge used to measure the pitch of the thread. This bolt has 13 threads to the inch.

THREADED FASTENERS TERMINOLOGY Most of the threaded fasteners used on vehicles are cap screws. They are called cap screws when they are threaded into a casting. Automotive service technicians usually refer to these fasteners as bolts, regardless of how they are used. In this chapter, they are called bolts. Sometimes, studs are used for threaded fasteners. A stud is a short rod with threads on both ends. Often, a stud will have coarse threads on one end and fine threads on the other end. The end of the stud with coarse threads is screwed into the casting. A nut is used on the opposite end to hold the parts together. The fastener threads must match the threads in the casting or nut. The threads may be measured either in fractions of an inch (called fractional) or in metric units. The size is measured across the outside of the threads, called the crest of the thread. SEE FIGURE 8–1. THREAD SIZES

Fractional threads are either coarse or fine. The coarse threads are called Unified National Coarse (UNC), and the fine threads are called Unified National Fine (UNF). Standard combinations of sizes and number of threads per inch (called pitch) are used. Pitch can be measured with a thread pitch gauge as shown in FIGURE 8–2.

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The size of a metric bolt is specified by the letter M followed by the diameter in millimeters (mm) across the outside (crest) of the threads. Typical metric sizes would be M8 and M12. Fine metric threads are specified by the thread diameter followed by X and the distance between the threads measured in millimeters (M8 ⫻ 1.5). SEE FIGURE 8–4.

GRADES OF BOLTS Bolts are made from many different types of steel, and for this reason some are stronger than others. The strength or classification of a bolt is called the grade. The bolt heads are marked to indicate their grade strength. Graded bolts are commonly used in the suspension parts of the vehicle but can be used almost anywhere in the vehicle. The actual grade of bolts is two more than the number of lines on the bolt head. Metric bolts have a decimal number to indicate the grade. More lines or a higher grade number indicate a stronger bolt. Higher grade bolts usually have threads that are rolled rather than cut, which also makes them stronger. SEE FIGURE 8–5. In some cases, nuts and machine screws have similar grade markings. CAUTION: Never use hardware store (nongraded) bolts, studs, or nuts on any vehicle steering, suspension, or brake component. Always use the exact size and grade of hardware that is specified and used by the vehicle manufacturer.

FIGURE 8–5 Stronger threads are created by cold-rolling a heattreated bolt blank instead of cutting the threads using a die.

TENSILE STRENGTH Graded fasteners have a higher tensile strength than nongraded fasteners. Tensile strength is the maximum stress used under tension (lengthwise force) without causing failure of the fastener. Tensile strength is specified in pounds per square inch (PSI). See the following chart that shows the grade and specified tensile strength. The strength and type of steel used in a bolt is supposed to be indicated by a raised mark on the head of the bolt. The type of mark depends on the standard to which the bolt was manufactured. Most often, bolts used in machinery are made to SAE Standard J429. Metric bolt tensile strength property class is shown on the head of the bolt as a number, such as 4.6, 8.8, 9.8, and 10.9; the higher the number, the stronger the bolt. SEE FIGURE 8–6. SAE Bolt Designations SAE Grade No. Size Range

Tensile Strength, PSI

1

1/4 through 1-1/2

60,000

2

1/4 through 3/4 74,000 60,000 7/8 through 1-1/2

5

1/4 through 1 1-1/8 through 1-1/2

5.2

Head Marking

Low or medium carbon steel

120,000 105,000

Medium carbon steel, quenched & tempered

1/4 through 1

120,000

Low carbon martensite steel*, quenched & tempered

7

1/4 through 1-1/2

133,000

Medium carbon alloy steel, quenched & tempered

8

1/4 through 1-1/2

150,000

Medium carbon alloy steel, quenched & tempered

8.2

1/4 through 1

150,000

Low carbon Martensite steel*, quenched & tempered

The American National System is one method of sizing fasteners.

FIGURE 8–4 The metric system specifies fasteners by diameter, length, and pitch.

Material

*Martensite steel is steel that has been cooled rapidly, thereby increasing its hardness. It is named after a German metallurgist, Adolf Martens.

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4.6

60,000

8.8

120,000

9.8

130,000

10.9

150,000

METRIC CLASS APPROXIMATE MAXIMUM POUND FORCE PER SQUARE INCH

FIGURE 8–7 Types of lock nuts. On the left, a nylon ring; in the center, a distorted shape; and on the right, a castle for use with a cotter key.

TECH TIP A 1/2 In. Wrench Does Not Fit a 1/2 In. Bolt A common mistake made by persons new to the automotive field is to think that the size of a bolt or nut is the size of the head. The size of the bolt or nut (outside diameter of the threads) is usually smaller than the size of the wrench or socket that fits the head of the bolt or nut. Examples are given in the following table. Wrench Size

FIGURE 8–8 A typical bottoming tap used to create threads in holes that are not open, but stop in a casting, such as an engine block.

TAPS AND DIES Taps and dies are used to cut threads. Taps are used to cut threads in holes drilled to an exact size depending on the size of the tap. A die is used to cut threads on round rods or studs. Most taps and dies come as a complete set for the most commonly used fractional and metric threads.

*European (Système International d’Unités-SI) metric.

HINT: An open-end wrench can be used to gauge bolt sizes. A 3/8 in. wrench will fit the threads of a 3/8 in. bolt.

NUTS Most nuts used on cap screws have the same hex size as the cap screw head. Some inexpensive nuts use a hex size larger than the cap screw head. Metric nuts are often marked with dimples to show their strength. More dimples indicate stronger nuts. Some nuts and cap screws use interference fit threads to keep them from accidentally loosening. This means that the shape of the nut is slightly distorted or that a section of the threads is deformed. Nuts can also be kept from loosening with a nylon washer fastened in the nut or with a nylon patch or strip on the threads. SEE FIGURE 8–7. NOTE: Most of these “locking nuts” are grouped together and are commonly referred to as prevailing torque nuts. This means that the nut will hold its tightness or torque and not loosen with movement or vibration. Most prevailing torque nuts should be replaced whenever removed to ensure that the nut will not loosen during service. Always follow the manufacturer’s recommendations. Anaerobic sealers, such as Loctite®, are used on the threads where the nut or cap screw must be both locked and sealed.

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TAPS

There are two commonly used types of taps, including:

Taper tap. This is the most commonly used tap and is designed to cut threads by gradually enlarging the threaded hole.

Bottoming tap. This tap has a flat bottom instead of a tapered tip to allow it to cut threads to the bottom of a drilled hole. SEE FIGURE 8–8.

All taps must be used in the proper size hole called a “tap drill size.” This information is often stamped on the tap itself or in a chart that is included with a tap and die tool set. SEE FIGURE 8–9.

DIES

A die is a hardened steel round cutter with teeth on the inside of the center hole. SEE FIGURE 8–10. A die is rotated using a die handle over a rod to create threads.

PROPER USE OF TAPS AND DIES

Taps and dies are used to cut threads on rods in the case of a die or in a hole for a tap. A small tap can be held using a T-handle tap wrench but for larger taps a tap handle is needed to apply the needed force to cut threads. SEE FIGURES 8–11A AND 8–11B. TAP USAGE. Be sure that the hole is the correct size for the tap and start by inserting the tap straight into the hole. Lubricate the tap using tapping lubricant. Rotate the tap about one full turn clockwise, then reverse the direction of the tap one-half turn to break the chip that was created. Repeat the procedure until the hole is completely threaded.

DIE HANDLE

FIGURE 8–12 A die handle used to rotate a die while cutting threads on a metal rod.

FIGURE 8–10 A die is used to cut threads on a metal rod. T-HANDLE TAP WRENCH

FIGURE 8–14 A thread chaser is shown at the top compared to a tap on the bottom. A thread chaser is used to clean threads without removing metal.

THREAD PITCH GAUGE (a) HAND TAP WRENCH

(b)

FIGURE 8–11 (a) A T-handle is used to hold and rotate small taps. (b) A tap wrench is used to hold and drive larger taps. DIE USAGE. A die should be used on the specified diameter rod for the size of the thread. Install the die securely into the die handle. SEE FIGURE 8–12. Lubricate the die and the rod and place the die onto the end of the rod to be threaded. Rotate the die handle one full turn clockwise, then reverse the direction and rotate the die handle about a half turn counterclockwise to break the chip that was created. Repeat the process until the threaded portion has been completed.

A thread pitch gauge is a hand tool that has the outline of various thread sizes machined on stamped blades. To determine the thread pitch size of a fastener, the technician matches the thread of the thread pitch gauge to the threads of the fastener. SEE FIGURE 8–13.

?

FREQUENTLY ASKED QUESTION

What Is the Difference Between a Tap and a Thread Chaser? A tap is a cutting tool and is designed to cut new threads. A thread chaser has more rounded threads and is designed to clean dirty threads without removing metal. Therefore, when cleaning threads, it is best to use a thread chaser rather than a tap to prevent the possibility of removing metal, which would affect the fit of the bolt being installed. SEE FIGURE 8–14

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PAN

ROUND

FLAT

HEX NUT

OVAL

HEXAGON

JAM NUT

FLAT WASHER

TRUSS

NYLON CASTLE LOCK NUT NUT

LOCK WASHER

STAR WASHER

ACORN NUT

STAR WASHER

FIGURE 8–16 Various types of nuts (top) and washers (bottom) serve different purposes and all are used to secure bolts or cap screws.

FIGURE 8–15 Sheet metal screws come with many head types.

SHEET METAL SCREWS Sheet metal screws are fully threaded screws with a point for use in sheet metal. Also called self-tapping screws, they are used in many places on the vehicle, including fenders, trim, and door panels. SEE FIGURE 8–15. These screws are used in unthreaded holes and the sharp threads cut threads as they are installed. This makes for a quick and easy installation when installing new parts, but the sheet metal screw can easily strip out the threads when used on the same part over and over, so care is needed. When reinstalling self-tapping screws, first turn the screw lightly backwards until you feel the thread drop into the existing thread in the screw hole. Then, turn the screw in; if it threads in easily, continue to tighten the screw. If the screw seems to turn hard, stop and turn it backwards about another half turn to locate the existing thread and try again. This technique can help prevent stripped holes in sheet metal and plastic parts. Sheet metal screws are sized according to their major thread diameter.

Size

Diameter Decimal (inch)

Diameter Nearest Fraction Inch

4 6 8 10 12 14

0.11 0.14 0.17 0.19 0.22 0.25

7/64 9/64 11/64 3/16 7/32 1/4

WASHERS Washers are often used under cap screw heads and under nuts. SEE FIGURE 8–16. Plain flat washers are used to provide an even clamping load around the fastener. Lock washers are added to prevent accidental loosening. In some accessories, the washers are locked onto the nut to provide easy assembly.

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Flat washers are placed underneath a nut to spread the load over a wide area and prevent gouging of the material. However, flat washers do not prevent a nut from loosening. Lock washers are designed to prevent a nut from loosening. Spring-type lock washers resemble a loop out of a coil spring. As the nut or bolt is tightened, the washer is compressed. The tension of the compressed washer holds the fastener firmly against the threads to prevent it from loosening. Lock washers should not be used on soft metal such as aluminum. The sharp ends of the steel washers would gouge the aluminum badly, especially if they are removed and replaced often. Another type of locking washer is the star washer. The teeth on a star washer can be external or internal, and they bite into the metal because they are twisted to expose their edges. Star washers are used often on sheet metal or body parts. They are seldom used on engines. The spring steel lock washer also uses the tension of the compressed washer to prevent the fastener from loosening. The waves in this washer make it look like a distorted flat washer.

SNAP RINGS AND CLIPS SNAP RINGS

Snap rings are not threaded fasteners, but instead attach with a springlike action. Snap rings are constructed of spring steel and are used to attach parts without using a threaded fastener. There are several different types of snap rings and most require the use of a special pair of pliers, called snap ring pliers, to release or install. The types of snap rings include:

Expanding (internal)

Contracting (external)

E-clip

C-clip

Holeless snap rings in both expanding and contracting styles.

SEE FIGURE 8–17.

DOOR PANEL CLIPS Interior door panels and other trim pieces are usually held in place with plastic clips. Due to the tapered and fluted shape, these clips are often called Christmas tree clips. SEE FIGURE 8–18. A special tool is often used to remove interior door panels without causing any harm. SEE FIGURE 8–19. CAUTION: Use extreme care when removing panels that use plastic or nylon clips. It is very easy to damage the door panel or clip during removal.

EXPANDING EXPANDING OR INTERNAL OR EXTERNAL

E-CLIP

EXPANDING CONTRACTING OR INTERNAL OR EXTERNAL

C-CLIP

FIGURE 8–17 Some different types of snap rings. An internal snap ring fits inside of a housing or bore, into a groove. An external snap ring fits into a groove on the outside of a shaft or axle. An E-clip fits into a groove in the outside of a shaft. A C-clip shown is used to retain a window regulator handle on its shaft.

FIGURE 8–22 All of the nuts shown are used by themselves except for the pal nut, which is used to lock another nut to a threaded fastener so they will not be loosened by vibration.

FIGURE 8–19 Plastic or metal trim tools are available to help the technician remove interior door panels and other trim without causing harm.

PINS

Cotter pins, also called a cotter key, are used to keep linkage or a threaded nut in place or to keep it retained. The word cotter is an Old English verb meaning “to close or fasten.” There are many other types of pins used in vehicles, including clevis pins, roll pins, and hair pins. SEE FIGURE 8–20. Pins are used to hold together shafts and linkages, such as shift linkages and cable linkages. The clevis pin is held in place with a cotter pin, while the taper and roll pins are driven in and held by friction. The hair pin snaps into a groove on a shaft.

RIVETS Rivets are used in many locations to retain components, such as window mechanisms, that do not require routine removal and/or do not have access to the back side for a nut. A drill is usually used to remove a rivet and a rivet gun is needed to properly install

a rivet. Some rivets are plastic and are used to hold some body trim pieces. The most common type of rivet is called a pop rivet because as the rivet tool applies a force to the shaft of the pop rivet, it causes the rivet to expand and tighten the two pieces together. When the shaft of the rivet, which looks like a nail, is pulled to its maximum, the shaft breaks, causing a “pop” sound. Rivets may be used in areas of the vehicle where a semipermanent attachment is needed and in places where there is no access to the back side of the workpiece. They are installed using a rivet gun or by peening with a ball-peen hammer. SEE FIGURE 8–21. Both types of blind rivets require the use of a rivet gun to install. The straight rivet is placed through the workpieces and then peened over with a ball-peen hammer or an air-operated tool. The plastic rivet is used with a rivet gun to install some body trim parts.

LOCKING NUTS Some nuts, called jam nuts, are used to keep bolts and screws from loosening. Jam nuts screw on top of a regular nut and jam against the regular nut to prevent loosening. A jam nut is so called because of its intended use, rather than a special design. Some jam nuts are thinner than a standard nut. Jam nuts are also called pal nuts. SEE FIGURE 8–22.

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CASTLELLATED NUT

FIGURE 8–24 Helical inserts look like small, coiled springs. The outside is a thread to hold the coil in the hole, and the inside is threaded to fit the desired fastener. HOLE IN THREADED STUD

COTTER PIN

FIGURE 8–23 A castellated nut is locked in place with a cotter pin. There are also self-locking nuts of various types. Some have threads that are bent inward to grip the threads of the bolt. Some are oval-shaped at one end to fit tightly on a bolt. Fiber lock nuts have a fiber insert near the top of the nut or inside it; this type of nut is also made with a plastic or nylon insert. When the bolt turns through the nut, it cuts threads in the fiber or plastic. This puts a drag on the threads that prevents the bolt from loosening. One of the oldest types of retaining nuts is the castle nut. It looks like a small castle, with slots for a cotter pin. A castellated nut is used on a bolt that has a hole for the cotter pin. SEE FIGURE 8–23.

HOW TO AVOID BROKEN FASTENERS Try not to break, strip, or round off fasteners in the first place. There are several ways that you can minimize the number of fasteners you damage. First, never force fasteners loose during disassembly. Taking a few precautionary steps will often prevent damage. If a bolt or nut will not come loose with normal force, try tightening it in slightly and then backing it out. Sometimes turning the fastener the other way will break corrosion loose, and the fastener will then come out easily. Another method that works well is to rest a punch on the head of a stubborn bolt and strike it a sharp blow with a hammer. Often this method will break the corrosion loose.

LEFT-HANDED THREADS Although rare, left-handed fasteners are occasionally found on engine assemblies. These fasteners will loosen when you turn them clockwise, and tighten when you turn them counterclockwise. Left-handed fasteners are used to fasten parts to the ends of rotating assemblies that turn counterclockwise, such as crankshafts and camshafts. Most automobile engines do not use left-handed threads; however, they will be found on many older motorcycle engines. Some left-handed fasteners are marked with an “L” on the bolt head for easy identification, others are not. Left-handed threads are also found inside some transaxles. PENETRATING OIL Penetrating oil is a lightweight lubricant similar to kerosene, which soaks into small crevices in the threads by capillary action. The chemical action of penetrating oils helps to

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break up and dissolve rust and corrosion. The oil forms a layer of boundary lubrication on the threads to reduce friction and make the fastener easier to turn. For best results, allow the oil time to soak in before removing the nuts and bolts. To increase the effectiveness of penetrating oil, tap on the bolt head or nut with a hammer, or alternately work the fastener back and forth with a wrench. This movement weakens the bond of the corrosion and lets more of the lubricant work down into the threads.

PROPER TIGHTENING Proper tightening of bolts and nuts is critical for proper clamping force, as well as to prevent breakage. All fasteners should be tightened using a torque wrench. A torque wrench allows the technician to exert a known amount of torque to the fasteners. However, rotating torque on a fastener does not mean clamping force because up to 80% of the torque used to rotate a bolt or nut is absorbed by friction by the threads. Therefore, for accurate tightening, two things must be performed:

The threads must be clean and lubricated if service information specifies that they be lubricated.

Always use a torque wrench to not only ensure proper clamping force, but also to ensure that all fasteners are tightened the same.

THREAD REPAIR INSERTS Thread repair inserts are used to replace the original threaded hole when it has become damaged beyond use. The original threaded hole is enlarged and tapped for threads and a threaded insert is installed to restore the threads to the original size.

HELICAL INSERTS A helical insert looks like a small, stainlesssteel spring. SEE FIGURE 8–24. To install a helical insert, a hole must be drilled to a specified oversize, and then it is tapped with a special tap designed for the thread inserts. The insert is then screwed into the hole. SEE FIGURE 8–25. The insert stays in the casting as a permanent repair and bolts can be removed and replaced without disturbing the insert. One advantage of a helical insert is that the original bolt can be used because the internal threads are the same size. When correctly installed, an insert is often stronger than the original threads, especially in aluminum castings. Some vehicle manufacturers, such as BMW, specify that the threads be renewed using an insert if the cylinder head has

FIGURE 8–25 The insert provides new, stock-size threads inside an oversize hole so that the original fastener can be used.

FIGURE 8–27 This solid-bushing insert is threaded on the outside, to grip the workpiece. The inner threads match the desired bolt size.

6. Remove the mandrel by unscrewing it from the insert, and then use a small punch or needle-nose pliers to break off the tang at the base of the insert. Never leave the tang in the bore. The finished thread is ready for use immediately.

THREADED INSERTS

FIGURE 8–26 Heli-Coil® kits, available in a wide variety of sizes, contain everything needed to repair a damaged hole back to its original size.

to be removed and reinstalled. Plus many high-performance engine rebuilders install inserts in blocks, manifolds, and cylinder heads as a precaution. One of the best known of the helical fasteners is the Heli-Coil®, manufactured by Heli-Coil® Products. To install Heli-Coil® inserts, you will need to have a thread repair kit. The kit includes a drill bit, tap, installation mandrel, and inserts. Repair kits are available for a wide variety of diameters and pitch to fit both American Standard and metric threads. A simple kit contains the tooling for one specific thread size. Master kits that cover a range of sizes are also available. Installing an insert is similar to tapping new threads. A summary of the procedures includes:

Threaded inserts are tubular, casehardened, solid steel wall pieces that are threaded inside and outside. The inner thread of the insert is sized to fit the original fastener of the hole to be repaired. The outer thread design will vary. These may be self-tapping threads that are installed in a blank hole, or machine threads that require the hole to be tapped. Threaded inserts return a damaged hole to original size by replacing part of the surrounding casting so drilling is required. Most inserts fit into three categories.

Self-tapping

Solid-bushing

Key-locking

SELF-TAPPING INSERTS The external threads of a selftapping insert are designed to cut their own way into a casting. This eliminates the need of running a tap down the hole. To install a typical self-tapping insert, follow this procedure. 1. Drill out the damaged threads to open the hole to the proper size, using the specified size drill bit. 2. Select the proper insert and mandrel. As with Heli-Coils®, the drill bit, inserts, and mandrel are usually available as a kit.

1. Select the Heli-Coil® kit designed for the specific diameter and thread pitch of the hole to be repaired. SEE FIGURE 8–26.

3. Thread the insert onto the mandrel. Use a tap handle or wrench to drive the insert into the hole. Because the insert will cut its own path into the hole, it may require a considerable amount of force to drive the insert in.

2. Use the drill bit supplied with the kit. The drill size is also specified on the Heli-Coil® tap, to open up the hole to the necessary diameter and depth.

4. Thread the insert in until the nut or flange at the bottom of the mandrel touches the surface of the workpiece. This is the depth stop to indicate the insert is seated.

3. Tap the hole with the Heli-Coil® tap, being sure to lubricate the tap. Turn it in slowly and rotate counterclockwise occasionally to break the chip that is formed.

5. Hold the nut or flange with a wrench, and turn the mandrel out of the insert. The threads are ready for immediate use.

4. Thread an insert onto the installation mandrel until it seats firmly. Apply a light coating of the recommended thread locking compound to the external threads of the insert. 5. Use the mandrel to screw the insert into the tapped hole. Once started, spring tension prevents the insert from unscrewing. Stop when the top of the insert is 1/4 to 1/2 turn below the surface.

SOLID-BUSHING INSERTS

The external threads of solidbushing inserts are ground to a specific thread pitch, so you will have to run a tap into the hole. SEE FIGURE 8–27. Some inserts use a machine thread so a standard tap can be used; others have a unique thread and you have to use a special tap. The thread inserts come with a matching installation kit. SEE FIGURE 8–28.

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FIGURE 8–30 Use a special tap for the insert. (a)

(b)

(c)

(d)

(e)

FIGURE 8–28 A Timesert® kit includes the drill (a), the recess cutter (b), a special tap (c), the installer (d), and the Timesert® threaded bushing (e).

FIGURE 8–31 Put some thread-locking compound on the insert.

5. Remove the installation driver, and the new threads are ready for service with the original fastener. FIGURE 8–29 Drill out the damaged threads with the correct bit. To install threaded inserts, follow this procedure. 1. Drill out the damaged threads to open the hole to the proper size. The drill bit supplied with the kit must be the one used because it is properly sized to the tap. SEE FIGURE 8–29. 2. Cut the recess in the top of the hole with the special tool, then clean the hole with a brush or compressed air.

KEY-LOCKING INSERTS Key-locking inserts are similar to solid-bushing inserts, but are held in place by small keys. After the insert has been installed, the keys are driven into place—perpendicular to the threads—to keep the insert from turning out. A typical installation procedure includes the following steps. 1. Drill out the damaged thread with the specified drill size. 2. Tap the drilled hole with the specified tap.

3. Use the previously detailed tapping procedures to thread the hole. SEE FIGURE 8–30. Be sure to tap deep enough; the top of the insert must be flush with the casting surface.

3. After putting thread locking compound on the insert, use the mandrel to screw the insert into the tapped hole until it is slightly below the surface. SEE FIGURE 8–31. The keys act as a depth stop and prevent the insert from turning.

4. Thread the insert onto the installation driver, using the driver to screw the insert into the hole. Some inserts require that a thread-locking compound be applied; others go in dry.

4. Drive the keys down using the driver supplied with the insert kit. Be sure the keys are flush with the top of the insert. SEE FIGURES 8–32 AND 8–33.

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FIGURE 8–32 Use the driver to drive the keys down flush with the surface of the workpiece.

FIGURE 8–33 The insert and insert locks should be below the surface of the workpiece.

REVIEW QUESTIONS 1. What is the difference between a bolt and a stud?

4. How do prevailing torque nuts work?

2. How is the size of a metric bolt expressed?

5. How are threaded inserts installed?

3. What is meant by the grade of a threaded fastener?

CHAPTER QUIZ 1. The thread pitch of a bolt is measured in what units? a. Millimeters b. Threads per inch c. Fractions of an inch d. Both a and b 2. Technician A says that the diameter of a bolt is the same as the wrench size used to remove or install the fastener. Technician B says that the length is measured from the top of the head of the bolt to the end of the bolt. Which technician is correct? a. Technician A only b. Technician B only c. Both Technicians A and B d. Neither Technician A nor B 3. The grade of a fastener, such as a bolt, is a measure of its ______________. a. Tensile strength c. Finish b. Hardness d. Color 4. Which of the following is a metric bolt? a. 5/16 ⫺ 18 c. M12 ⫻ 1.5 b. 1/2 ⫺ 20 d. 8 mm 5. A bolt that is threaded into a casting is often called a ______________. a. Stud c. Block bolt b. Cap screw d. Crest bolt

6. The marks (lines) on the heads of bolts indicate ______________. a. Size c. Tensile strength b. Grade d. Both b and c 7. A bolt that requires a 1/2 in. wrench to rotate is usually what size when measured across the threads? a. 1/2 in. c. 3/8 in. b. 5/16 in. d. 7/16 in. 8. A screw that can make its own threads when installed is called a ______________ screw. a. Sheet metal b. Tapered c. Self-tapping d. Both a and c 9. All of the following are types of clips except ______________. a. E-clip b. Cotter c. C-clip d. Internal 10. What type of fastener is commonly used to retain interior door panels? a. Christmas tree clips b. E-clips c. External clips d. Internal clips

WRENCHES Wrenches are the most used hand tool by service technicians. Most wrenches are constructed of forged alloy steel, usually chromevanadium steel. SEE FIGURE 9–1. After the wrench is formed, it is hardened, tempered to reduce brittleness, and then chrome plated. Wrenches are available in both fractional and metric sizes. There are several types of wrenches.

OPEN-END WRENCH An open-end wrench is often used to loosen or tighten bolts or nuts that do not require a lot of torque. An open-end wrench can be easily placed on a bolt or nut with an angle of 15 degrees, which allows the wrench to be flipped over and used again to continue to rotate the fastener. The major disadvantage of an open-end wrench is the lack of torque that can be applied due to the fact that the open jaws of the wrench only contact two flat surfaces of the fastener. An open-end wrench has two different sizes, one at each end. SEE FIGURE 9–2. BOX-END WRENCH A box-end wrench is placed over the top of the fastener and grips the points of the fastener. A box-end wrench is angled 15 degrees to allow it to clear nearby objects. SEE FIGURE 9–3. Therefore, a box-end wrench should be used to loosen or to tighten fasteners. A box-end wrench is also called a close-end wrench. A box-end wrench has two different sizes, one at each end. SEE FIGURE 9–4. COMBINATION WRENCH

Most service technicians purchase combination wrenches, which have the open end at one end and the same size box end on the other. SEE FIGURE 9–5.

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FIGURE 9–1 A forged wrench after it has been forged but before the flashing, extra material around the wrench, has been removed.

A combination wrench allows the technician to loosen or tighten a fastener using the box end of the wrench, turn it around, and use the open end to increase the speed of rotating the fastener.

ADJUSTABLE WRENCH

An adjustable wrench is often used where the exact size wrench is not available or when a large nut, such as a wheel spindle nut, needs to be rotated but not tightened. An adjustable wrench should not be used to loosen or tighten fasteners because the torque applied to the wrench can cause the movable jaws to loosen their grip on the fastener, causing it to become rounded. SEE FIGURE 9–6.

LINE WRENCHES

Line wrenches are also called flare-nut wrenches, fitting wrenches, or tube-nut wrenches and are designed to grip almost all the way around a nut used to retain a fuel or refrigerant line, and yet be able to be installed over the line. SEE FIGURE 9–7. SAFE USE OF WRENCHES. Wrenches should be inspected before use to be sure they are not cracked, bent, or damaged. All wrenches should be cleaned after use before being returned to the toolbox.

1/2

6

9/1

15˚

15˚

FIGURE 9–2 A typical open-end wrench. The size is different on each end and notice that the head is angled 15 degrees at each end.

FIGURE 9–3 A typical box-end wrench is able to grip the bolt or nut at points completely around the fastener. Each end is a different size.

FIGURE 9–7 The end of a typical line wrench, which shows that it is capable of grasping most of the head of the fitting.

ANGLED SHANK RATCHET REVERSING LEVER 15˚

FIGURE 9–4 The end of a box-end wrench is angled 15 degrees to allow clearance for nearby objects or other fasteners. BOX END OPEN END

1/2 - 3/4 INCH SQUARE DRIVE LUG

FIGURE 9–8 A typical ratchet used to rotate a socket. A ratchet makes a ratcheting noise when it is being rotated in the opposite direction from loosening or tightening. A knob or lever on the ratchet allows the user to switch directions.

FIGURE 9–5 A combination wrench has an open end at one end and a box end at the other with the same size at each end.

OVERALL LENGTH

FIGURE 9–9 A typical flex handle used to rotate a socket, also called a breaker bar because it usually has a longer handle than a ratchet and, therefore, can be used to apply more torque to a fastener than a ratchet.

FIGURE 9–6 An adjustable wrench. Adjustable wrenches are sized by the overall length of the wrench and not by how far the jaws open. Common sizes of adjustable wrenches include 8, 10, and 12 in. Always use the correct size of wrench for the fastener being loosened or tightened to help prevent the rounding of the flats of the fastener. When attempting to loosen a fastener, pull a wrench—do not push a wrench. If a wrench is pushed, your knuckles can be hurt when forced into another object if the fastener breaks loose.

RATCHETS, SOCKETS, AND EXTENSIONS A socket fits over the fastener and grips the points and/or flats of the bolt or nut. The socket is rotated (driven) using either a long bar called a breaker bar (flex handle) or a ratchet. SEE FIGURES 9–8 AND 9–9.

FIGURE 9–13 Using a torque wench to tighten connecting rod nuts on an engine.

NUT

FIGURE 9–11 A 6-point socket fits the head of the bolt or nut on all sides. A 12-point socket can round off the head of a bolt or nut if a lot of force is applied. FIGURE 9–14 A beam-type torque wrench that displays the torque reading on the face of the dial. The beam display is read as the beam deflects, which is in proportion to the amount of torque applied to the fastener.

TECH TIP Right to Tighten FIGURE 9–12 A crowfoot socket is designed to reach fasteners using a ratchet or breaker bar with an extension.

A ratchet turns the socket in only one direction and allows the rotating of the ratchet handle back and forth in a narrow space. Socket extensions and universal joints are also used with sockets to allow access to fasteners in restricted locations. Sockets are available in various drive sizes, including 1/4 in., 3/8 in., and 1/2 in. sizes for most automotive use. SEE FIGURES 9–10 AND 9–11. Many heavy-duty truck and/or industrial applications use 3/4 in. and 1 in. sizes. The drive size is the distance of each side of the square drive. Sockets and ratchets of the same size are designed to work together.

CROWFOOT SOCKETS A crowfoot socket is a socket that is an open-end or line wrench to allow access to fasteners that cannot be reached using a conventional wrench. SEE FIGURE 9–12. Crowfoot sockets are available in the following categories.

Fractional inch open-end wrench

Metric open-end wrench

Fractional line wrench

Metric line wrench

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It is sometimes confusing which way to rotate a wrench or screwdriver, especially when the head of the fastener is pointing away from you. To help visualize while looking at the fastener, say “righty tighty, lefty loosey.”

TORQUE WRENCHES

Torque wrenches are socket turning handles that are designed to apply a known amount of force to the fastener. There are two basic types of torque wrenches. 1. A clicker-type torque wrench is first set to the specified torque and then it “clicks” when the set torque value has been reached. When force is removed from the torque wrench handle, another click is heard. The setting on a clicker-type torque wrench should be set back to zero after use and checked for proper calibration regularly. SEE FIGURE 9–13. 2. A beam- or dial-type torque wrench is used to measure torque, but instead of presetting the value, the actual torque is displayed on the dial of the wrench as the fastener is being tightened. Beam-type torque wrenches are available in 1/4 in., 3/8 in., and 1/2 in. drives and both English and metric units. SEE FIGURE 9–14.

SAFE USE OF SOCKETS AND RATCHETS. Always use the proper size socket that correctly fits the bolt or nut. All sockets and ratchets

?

FREQUENTLY ASKED QUESTION

Is It Lb-Ft or Ft-Lb of Torque? The unit for torque is expressed as a force times the distance (leverage) from the object. Therefore, the official unit for torque is lb-ft (pound-feet) or newton-meters (a force times a distance). However, it is commonly expressed in ft-lb and even some torque wrenches are labeled with this unit.

TECH TIP Double-Check the Specifications Misreading torque specifications is easy to do but can have serious damaging results. Specifications for fasteners are commonly expressed lb-ft. Many smaller fasteners are tightened to specifications expressed in lb-in. 1 lb-ft ⫽ 12 lb-in.

FIGURE 9–15 Torque wrench calibration checker.

Therefore, if a fastener were to be accidentally tightened to 24 lb-ft instead of 24 lb-in., the actual torque applied to the fastener will be 288 lb-in. instead of the specified 24 lb-in. This extra torque will likely break the fastener, but it could also warp or distort the part being tightened. Always double-check the torque specifications.

REGULAR SOCKET DEEP SOCKET

TECH TIP Use Socket Adapters with Caution

FIGURE 9–16 Deep sockets allow access to the nut that has a stud plus other locations needing great depth, such as spark plugs.

TECH TIP Check Torque Wrench Calibration Regularly Torque wrenches should be checked regularly. For example, Honda has a torque wrench calibration setup at each of their training centers. It is expected that a torque wrench be checked for accuracy before every use. Most experts recommend that torque wrenches be checked and adjusted as needed at least every year and more often if possible. SEE FIGURE 9–15.

Socket adapters are available and can be used for different drive size sockets on a ratchet. Combinations include: • • • •

Using a larger drive ratchet or breaker bar on a smaller size socket can cause the application of too much force to the socket, which could crack or shatter. Using a smaller size drive tool on a larger socket will usually not cause any harm, but would greatly reduce the amount of torque that can be applied to the bolt or nut.

TECH TIP

should be cleaned after use before being placed back into the toolbox. Sockets are available in short and deep well designs. SEE FIGURE 9–16. Also select the appropriate drive size. For example, for small work, such as on the dash, select a 1/4 in. drive. For most general service work, use a 3/8 in. drive and for suspension and steering and other large fasteners, select a 1/2 in. drive. When loosening a fastener, always pull the ratchet toward you rather than push it outward.

Avoid Using “Cheater Bars” Whenever a fastener is difficult to remove, some technicians will insert the handle of a ratchet or a breaker bar into a length of steel pipe. The extra length of the pipe allows the technician to exert more torque than can be applied using the drive handle alone. However, the extra torque can easily overload the socket and ratchet, causing them to break or shatter, which could cause personal injury.

H A N D T OOL S

71

BLADE WIDTH

FIGURE 9–17 A flat-tip (straight blade) screwdriver. The width of the blade should match the width of the slot in the fastener being loosened or tightened.

FIGURE 9–18 Two stubby screwdrivers that are used to access screws that have limited space above. A straight blade is on top and a #2 Phillips screwdriver is on the bottom.

FIGURE 9–19 An offset screwdriver is used to install or remove fasteners that do not have enough space above to use a conventional screwdriver.

FIGURE 9–20 An impact screwdriver used to remove slotted or Phillips head fasteners that cannot be broken loose using a standard screwdriver.

?

FREQUENTLY ASKED QUESTION

What Are Torx and Robertson Screwdrivers?

SCREWDRIVERS Many smaller fasteners are removed and installed by using a screwdriver. Screwdrivers are available in many sizes and tip shapes. The most commonly used screwdriver is called a flat tip or straight blade. Flat-tip screwdrivers are sized by the width of the blade and this width should match the width of the slot in the screw. SEE FIGURE 9–17. CAUTION: Do not use a screwdriver as a pry tool or as a chisel. Always use the proper tool for each application. Another type of commonly used screwdriver is called a Phillips screwdriver, named for Henry F. Phillips, who invented the crosshead screw in 1934. Due to the shape of the crosshead screw and screwdriver, a Phillips screw can be driven with more torque than can be achieved with a slotted screw. A Phillips head screwdriver is specified by the length of the handle and the size of the point at the tip. A #1 tip has a sharp point, a #2 tip is the most commonly used, and a #3 tip is blunt and is only used for larger sizes of Phillips head fasteners. For example, a #2 ⫻ 3 in. Phillips screwdriver would typically measure 6 in. from the tip of the blade to the end of the handle (3 in. long handle and 3 in. long blade) with a #2 tip. Both straight blade and Phillips screwdrivers are available with a short blade and handle for access to fasteners with limited room. SEE FIGURE 9–18.

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A Torx is a six-pointed star-shaped tip that was developed by Camcar (formerly Textron) to offer greater loosening and tightening torque than is possible with a straight (flat tip) or Phillips screwdriver. Torx is commonly used in the automotive field for fastening of many components. P. L. Robertson invented the Robertson screw and screwdriver in 1908, which uses a square-shaped tip with a slight taper. The Robertson screwdriver uses color-coded handles because different size screws require different tip sizes. Robertson screws are commonly used in Canada and in the recreational vehicle (RV) industry in the United States.

OFFSET SCREWDRIVERS

Offset screwdrivers are used in places where a conventional screwdriver cannot fit. An offset screwdriver is bent at the ends and is used similar to a wrench. Most offset screwdrivers have a straight blade at one end and a Phillips end at the opposite end. SEE FIGURE 9–19.

IMPACT SCREWDRIVER

An impact screwdriver is used to break loose or tighten a screw. A hammer is used to strike the end after the screwdriver holder is placed in the head of the screw and rotated in the desired direction. The force from the hammer blow does two things: It applies a force downward holding the tip of the screwdriver in the slot and then applies a twisting force to loosen (or tighten) the screw. SEE FIGURE 9–20.

FIGURE 9–21 A typical ball-peen hammer.

FIGURE 9–22 A rubber mallet used to deliver a force to an object without harming the surface.

FIGURE 9–23 A dead-blow hammer that was left outside in freezing weather. The plastic covering was damaged, which destroyed this hammer. The lead shot is encased in the metal housing and then covered.

SAFE USE OF SCREWDRIVERS. Always use the proper type and size screwdriver that matches the fastener. Try to avoid pressing down on a screwdriver because if it slips, the screwdriver tip could go into your hand, causing serious personal injury. All screwdrivers should be cleaned after use. Do not use a screwdriver as a pry bar; always use the correct tool for the job.

SLIP-JOINT

SMALLER

HAMMERS AND MALLETS HAMMERS Hammers and mallets are used to force objects together or apart. The shape of the back part of the hammer head (called the peen) usually determines the name. For example, a ball-peen hammer has a rounded end like a ball and it is used to straighten oil pans and valve covers, using the hammer head, and for shaping metal, using the ball peen. SEE FIGURE 9–21. NOTE: A claw hammer has a claw used to remove nails and is not used for automotive service. A hammer is usually sized by the weight of the head of the hammer and the length of the handle. For example, a commonly used ball-peen hammer has an 8 oz head with an 11 in. handle.

MALLETS

Mallets are a type of hammer with a large striking surface, which allows the technician to exert force over a larger area than a hammer, so as not to harm the part or component. Mallets are made from a variety of materials including rubber, plastic, or wood. SEE FIGURE 9–22. A shot-filled plastic hammer is called a dead-blow hammer. The small lead balls (shot) inside a plastic head prevent the hammer from bouncing off of the object when struck. SEE FIGURE 9–23. SAFE USE OF HAMMERS AND MALLETS. All mallets and hammers should be cleaned after use and not exposed to extreme temperatures. Never use a hammer or mallet that is damaged in any way and always use caution to avoid doing damage to the components and the surrounding area. Always follow the hammer manufacturer’s recommended procedures and practices.

LARGER

FIGURE 9–24 Typical slip-joint pliers, which are also common household pliers. The slip joint allows the jaws to be opened to two different settings.

PLIERS SLIP-JOINT PLIERS

Pliers are capable of holding, twisting, bending, and cutting objects and are an extremely useful classification of tools. The common household type of pliers is called the slip-joint pliers. There are two different positions where the junction of the handles meets to achieve a wide range of sizes of objects that can be gripped. SEE FIGURE 9–24.

MULTIGROOVE ADJUSTABLE PLIERS For gripping larger objects, a set of multigroove adjustable pliers is a commonly used tool of choice by many service technicians. Originally designed to remove the various size nuts holding rope seals used in water pumps, the name water pump pliers is also used. SEE FIGURE 9–25. LINESMAN’S PLIERS Linesman’s pliers are specifically designed for cutting, bending, and twisting wire. While commonly used by construction workers and electricians, linesman’s pliers are very useful tools for the service technician who deals with wiring. The center parts of the jaws are designed to grasp round objects such as pipe or tubing without slipping. SEE FIGURE 9–26. DIAGONAL PLIERS Diagonal pliers are designed for cutting only. The cutting jaws are set at an angle to make it easier to cut

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MULTI-GROOVES FOR JAW WIDTH ADJUSTMENT

FIGURE 9–28 Needle-nose pliers are used where there is limited access to a wire or pin that needs to be installed or removed.

FIGURE 9–25 Multigroove adjustable pliers are known by many names, including the trade name Channel Locks. FLAT GRIP

RELEASE LEVER

CUTS SOFT WIRE

PIPE GRIP

FIGURE 9–29 Locking pliers are best known by their trade name Vise-Grip®.

SIDE CUTTERS

TECH TIP JOINT CUTTERS

Brand Name Versus Proper Term

GRIPS SMALL OBJECTS

FIGURE 9–26 A linesman’s pliers are very useful because they can help perform many automotive service jobs.

Technicians often use slang or brand names of tools rather than the proper term. This results in some confusion for new technicians. Some examples are given in the following table. Brand Name

Use Chalk Often soft metal particles can become stuck in a file, especially when using it to file aluminum or other soft metals. Rub some chalk into the file before using it to prevent this from happening.

PULLING OUT AND SPREADING COTTER PIN

FIGURE 9–27 Diagonal-cut pliers are another common tool that has many names. wires. Diagonal pliers are also called side cuts or dikes. These pliers are constructed of hardened steel and they are used mostly for cutting wire. SEE FIGURE 9–27.

NEEDLE-NOSE PLIERS

Needle-nose pliers are designed to grip small objects or objects in tight locations. Needle-nose pliers have long, pointed jaws, which allow the tips to reach into narrow openings or groups of small objects. SEE FIGURE 9–28.

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Most needle-nose pliers have a wire cutter located at the base of the jaws near the pivot. There are several variations of needlenose pliers, including right angle jaws or slightly angled to allow access to certain cramped areas.

LOCKING PLIERS Locking pliers are adjustable pliers that can be locked to hold objects from moving. Most locking pliers also have wire cutters built into the jaws near the pivot point. Locking pliers come in a variety of styles and sizes and are commonly referred to by their trade name Vise-Grip®. The size is the length of the pliers, not how far the jaws open. SEE FIGURE 9–29. SAFE USE OF PLIERS. Pliers should not be used to remove any bolt or other fastener. Pliers should only be used when specified for use by the vehicle manufacturer.

FIGURE 9–30 Snap-ring pliers are also called lock-ring pliers and are designed to remove internal and external snap rings (lock rings).

TRIANGULAR

FIGURE 9–33 A utility knife uses replaceable blades and is used to cut carpet and other materials.

CUTTERS

HALF ROUND

SNIPS

ROUND

FLAT HANDLE

FIGURE 9–31 Files come in many different shapes and sizes. Never use a file without a handle.

Service technicians are often asked to fabricate sheet metal brackets or heat shields and need to use one or more types of cutters available. The simplest is called tin snips, which are designed to make straight cuts in a variety of materials, such as sheet steel, aluminum, or even fabric. A variation of the tin snips is called aviation tin snips. There are three designs of aviation snips including one designed to cut straight (called a straight cut aviation snip), one designed to cut left (called an offset left aviation snip), and one designed to cut right (called an offset right aviation snip). The handles are color coded for easy identification. These include yellow for straight, red for left, and green for right. SEE FIGURE 9–32.

SNAP-RING PLIERS

Snap-ring pliers are used to remove and install snap rings. Many snap-ring pliers are designed to be able to remove and install inward, as well as outward, expanding snap rings. Snap-ring pliers can be equipped with serrated-tipped jaws for grasping the opening in the snap ring, while others are equipped with points, which are inserted into the holes in the snap ring. SEE FIGURE 9–30.

FILES

Files are used to smooth metal and are constructed of hardened steel with diagonal rows of teeth. Files are available with a single row of teeth called a single-cut file, as well as two rows of teeth cut at an opposite angle called a double-cut file. Files are available in a variety of shapes and sizes from small flat files, halfround files, and triangular files. SEE FIGURE 9–31.

SAFE USE OF FILES. Always use a file with a handle. Because files only cut when moved forward, a handle must be attached to prevent possible personal injury. After making a forward strike, lift the file and return the file to the starting position; avoid dragging the file backward.

UTILITY KNIFE A utility knife uses a replaceable blade and is used to cut a variety of materials such as carpet, plastic, wood, and paper products, such as cardboard. SEE FIGURE 9–33. SAFE USE OF CUTTERS. Whenever using cutters, always wear eye protection or a face shield to guard against the possibility of metal pieces being ejected during the cut. Always follow recommended procedures.

PUNCHES AND CHISELS PUNCHES A punch is a small diameter steel rod that has a smaller diameter ground at one end. A punch is used to drive a pin out that is used to retain two components. Punches come in a variety of sizes, which are measured across the diameter of the machined end. Sizes include 1/16 in., 1/8 in., 3/16 in., and 1/4 in. SEE FIGURE 9–34.

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CHAMFER

MUSHROOM

RIGHT

WRONG

FIGURE 9–36 Use a grinder or a file to remove the mushroom material on the end of a punch or chisel. PIN

FIGURE 9–34 A punch used to drive pins from assembled components. This type of punch is also called a pin punch.

SERRATED CAM

FIGURE 9–35 Warning stamped in the side of a punch warning that goggles should be worn when using this tool. Always follow safety warnings.

FIGURE 9–37 A stud remover uses an offset serrated wheel to grasp the stud so it will be rotated when a ratchet or breaker bar is used to rotate the assembly.

CUTTER

CHISELS

FORCING SCREW

A chisel has a straight, sharp cutting end that is used for cutting off rivets or to separate two pieces of an assembly. The most common design of chisel used for automotive service work is called a cold chisel. SAFE USE OF PUNCHES AND CHISELS. Always wear eye protection when using a punch or a chisel because the hardened steel is brittle and parts of the punch could fly off and cause serious personal injury. See the warning stamped on the side of this automotive punch in FIGURE 9–35. Punches and chisels can also have the top rounded off, which is called “mushroomed.” This material must be ground off to help avoid the possibility that the overhanging material is loosened and becomes airborne during use. SEE FIGURE 9–36.

REMOVERS Removers are tools used to remove damaged fasteners. A remover tool is not normally needed during routine service unless the fastener is corroded or has been broken or damaged by a previous attempt to remove the bolt or nut. To help prevent the need for a remover tool, all rusted and corroded fasteners should be sprayed with penetrating oil. Penetrating oil is a low viscosity oil that is designed to flow in between the threads of a fastener or other small separation between two parts. Commonly used penetrating oils include WD-40®, Kroil®, and CRC 5-56. CAUTION: Do not use penetrating oil as a lubricating oil because it is volatile and will evaporate soon after usage leaving little lubricant behind for protection.

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SCREW HEAD

FIGURE 9–38 A nut splitter is used to split a nut that cannot be removed. After the nut has been split, a chisel is then used to remove the nut.

Removers are a classification of tool used to remove stuck or broken fasteners. Over time, rust and corrosion can cause the threads of the fastener to be attached to the nut or the casting making it very difficult to remove. There are several special tools that can be used to remove damaged fasteners. Which one to use depends on the type of damage.

DAMAGED HEADS If the bolt head or a nut becomes damaged or rounded, there are two special tools that can be used, including:

Stud remover. A stud removal tool grips the part of the stud above the surface and uses a cam or wedge to grip the stud as it is being rotated by a ratchet or breaker bar. SEE FIGURE 9–37.

Nut splitter. A nut splitter is used to remove the nut by splitting it from the bolt. A nut splitter is used by inserting the cutter against a flat of the nut and tightening the threaded bolt of the splitter. The nut will be split away from the bolt and can then be removed. SEE FIGURE 9–38.

REPLACEABLE BLADE

FIGURE 9–41 A typical hacksaw that is used to cut metal. If cutting sheet metal or thin objects, a blade with more teeth should be used.

TECH TIP The Wax Trick FIGURE 9–39 A set of bolt extractors, commonly called easy outs.

Many times rusted fasteners can be removed by using heat to expand the metal and break the rust bond between the fastener and the nut or casting. Many technicians heat the fastener using a torch and then apply paraffin wax or a candle to the heated fastener. SEE FIGURE 9–40. The wax will melt and as the part cools, will draw the liquid wax down between the threads. After allowing the part to cool, attempt to remove the fastener. It will often be removed without any trouble.

?

FREQUENTLY ASKED QUESTION

I Broke Off an Easy Out—Now What?

FIGURE 9–40 Removing plugs or bolts is easier if the plug is first heated to cherry red color, using a torch, and then applying wax. During cooling, the wax flows in between the threads, making it easier to remove.

CAUTION: Do not rotate the entire nut splitter or damage to the cutting wedge will occur.

BROKEN BOLTS, STUDS, OR SCREWS

Often, bolts, studs, or screws break even with, or below the surface, making stud removal tools impossible to use. Bolt extractors are commonly called easy outs. An easy out is constructed of hardened steel with flutes or edges ground into the side in an opposite direction of most threads. SEE FIGURE 9–39.

NOTE: Always select the largest extractor that can be used to help avoid the possibility of breaking the extractor while attempting to remove the bolt. A hole is drilled into the center of a broken bolt. Then, the extractor (easy out) is inserted into the hole and rotated counterclockwise using a wrench. As the extractor rotates, the grooves grip tighter into the wall of the hole drilled in the broken bolt. As a result, most extractors are capable of removing most broken bolts.

An extractor (easy out) is hardened steel and removing this and the broken bolt is now a job for a professional machine shop. The part, which could be as large as an engine block, needs to be removed from the vehicle and taken to a machine shop that is equipped to handle this type of job. One method involves using an electrical discharge machine (EDM). An EDM uses a high amperage electrical current to produce thousands of arcs between the electrode and the broken tool. The part is submerged in a non-conducting liquid and each tiny spark vaporizes a small piece of the broken tool.

HACKSAWS A hacksaw is used to cut metals, such as steel, aluminum, brass, or copper. The cutting blade of a hacksaw is replaceable and the sharpness and number of teeth can be varied to meet the needs of the job. Use 14 or 18 teeth per inch (tpi) for cutting plaster or soft metals, such as aluminum and copper. Use 24 or 32 teeth per inch for steel or pipe. Hacksaw blades should be installed with the teeth pointing away from the handle. This means that a hacksaw cuts while the blade is pushed in the forward direction, and then pressure should be released as the blade is pulled rearward before repeating the cutting operation. SEE FIGURE 9–41. SAFE USE OF HACKSAWS. Check that the hacksaw is equipped with the correct blade for the job and that the teeth are pointed away from the handle. When using a hacksaw, move the hacksaw slowly away from you, then lift slightly and return for another cut.

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TECH TIP Hide Those from the Boss An apprentice technician started working for a dealership and put his top tool box on a workbench. Another technician observed that, along with a complete set of good-quality tools, the box contained several adjustable wrenches. The more experienced technician said, “Hide those from the boss.” If any adjustable wrench is used on a bolt or nut, the movable jaw often moves or loosens and starts to round the head of the fastener. If the head of the bolt or nut becomes rounded, it becomes that much more difficult to remove.

A beginning service technician may wish to start with a small set of tools before spending a lot of money on an expensive, extensive tool box. SEE FIGURES 9–42 AND 9–43.

FIGURE 9–43 A typical large tool box, showing just one of many drawers.

FIGURE 9–44 A seal puller being used to remove a seal from a rear axle.

HAMMER

TECH TIP Need to Borrow a Tool More than Twice? Buy It! Most service technicians agree that it is okay for a beginning technician to borrow a tool occasionally. However, if a tool has to be borrowed more than twice, then be sure to purchase it as soon as possible. Also, whenever a tool is borrowed, be sure that you clean the tool and let the technician you borrowed the tool from know that you are returning the tool. These actions will help in any future dealings with other technicians.

CALIPER BODY

TECH TIP The Valve Grinding Compound Trick Apply a small amount of valve grinding compound to a Phillips or Torx screw or bolt head. The gritty valve grinding compound “grips” the screwdriver or tool bit and prevents the tool from slipping up and out of the screw head. Valve grinding compound is available in a tube from most automotive parts stores.

BOOT DRIVER

FIGURE 9–45 A seal driver or installer is usually plastic and is designed to seat the seal.

ELECTRICAL HAND TOOLS SEAL PULLERS AND DRIVERS SEAL PULLERS

Grease seals are located on many automotive components, including brake rotors, transmission housings, and differentials. A seal puller is used to properly remove grease seals, as shown in FIGURE 9–44.

SEAL DRIVERS

A seal driver can be either plastic or metal, usually aluminum, and is used to seat the outer lip of a grease seal into the grease seal pocket. A seal is usually driven into position using a plastic mallet and a seal driver that is the same size as the outside diameter of the grease seal retainer. SEE FIGURE 9–45.

TEST LIGHTS

A test light is used to test for electricity. A typical automotive test light consists of a clear plastic screwdriver-like handle that contains a light bulb. A wire is attached to one terminal of the bulb, which the technician connects to a clean metal part of the vehicle. The other end of the bulb is attached to a point that can be used to test for electricity at a connector or wire. When there is power at the point and a good connection at the other end, the light bulb lights. SEE FIGURE 9–46.

SOLDERING GUNS

Electric soldering gun. This type of soldering gun is usually powered by 110 volt AC and often has two power settings expressed in watts. A typical electric soldering gun will

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BUTANE-POWERED

ELECTRIC

FIGURE 9–46 A typical 12 volt test light. produce from 85 to 300 watts of heat at the tip, which is more than adequate for soldering. SEE FIGURE 9–47.

Electric soldering pencil. This type of soldering iron is less expensive and creates less heat than an electric soldering gun. A typical electric soldering pencil (iron) creates 30 to 60 watts of heat and is suitable for soldering smaller wires and connections.

Butane-powered soldering iron. A butane-powered soldering iron is portable and very useful for automotive service work because an electrical cord is not needed. Most butanepowered soldering irons produce about 60 watts of heat, which is enough for most automotive soldering.

FIGURE 9–47 An electric soldering gun used to make electrical repairs. Soldering guns are sold by the wattage rating. The higher the wattage, the greater amount of heat created. Most solder guns used for automotive electrical work usually fall within the 60 to 160 watt range.

TECH TIP It Just Takes a Second Whenever removing any automotive component, it is wise to screw the bolts back into the holes a couple of threads by hand. This ensures that the right bolt will be used in its original location when the component or part is put back on the vehicle. Often, the same diameter of fastener is used on a component, but the length of the bolt may vary. Spending just a couple of seconds to put the bolts and nuts back where they belong when the part is removed can save a lot of time when the part is being reinstalled. Besides making certain that the right fastener is being installed in the right place, this method helps prevent bolts and nuts from getting lost or kicked away. How much time have you wasted looking for that lost bolt or nut?

In addition to a soldering iron, most service technicians who do electrical-related work should have the following:

Wire cutters

Wire strippers

Wire crimpers

Heat gun

A digital meter is a necessary tool for any electrical diagnosis and troubleshooting. A digital multimeter, abbreviated DMM, is usually capable of measuring the following units of electricity.

DC volts

AC volts

Ohms

Amperes

SAFETY TIPS FOR USING HAND TOOLS

fastener. (If heat is used on a bolt or nut to remove it, always replace it with a new part.)

Always use the proper tool for the job. If a specialized tool is required, use the proper tool and do not try to use another tool improperly.

Never expose any tool to excessive heat. High temperatures can reduce the strength (“draw the temper”) of metal tools.

Never use a hammer on any wrench or socket handle unless you are using a special “staking face” wrench designed to be used with a hammer.

Replace any tools that are damaged or worn.

The following safety tips should be kept in mind whenever you are working with hand tools.

Always pull a wrench toward you for best control and safety. Never push a wrench.

Keep wrenches and all hand tools clean to help prevent rust and to allow for a better, firmer grip.

Always use a 6-point socket or a box-end wrench to break loose a tight bolt or nut.

Use a box-end wrench for torque and an open-end wrench for speed.

Never use a pipe extension or other type of “cheater bar” on a wrench or ratchet handle. If more force is required, use a larger tool or use penetrating oil and/or heat on the frozen

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HAND TOOL MAINTENANCE Most hand tools are constructed of rust-resistant metals but they can still rust or corrode if not properly maintained. For best results and long tool life, the following steps should be taken.

Clean each tool before placing it back into the tool box.

Keep tools separated. Moisture on metal tools will start to rust more readily if the tools are in contact with another metal tool.

TECH TIP Use a Binder Clip A binder clip (size 1 1/4 in. wide) is used by wise technicians to help keep fender covers in place. SEE FIGURE 9–48. Binder clips are found at office supply stores.

Line the drawers of the tool box with a material that will prevent the tools from moving as the drawers are opened and closed. This helps to quickly locate the proper tool and size.

Release the tension on all “clicker-type” torque wrenches after use.

Keep the tool box secure.

FIGURE 9–48 A binder clip being used to keep a fender cover from falling.

REVIEW QUESTIONS 1. Why are wrenches offset 15 degrees?

4. Which type of screwdriver requires the use of a hammer or mallet?

2. What are the other names for a line wrench?

5. What is inside a dead-blow hammer?

3. What are the standard automotive drive sizes for sockets?

6. What type of cutter is available in left and right cutters?

CHAPTER QUIZ 1. When working with hand tools, always ______________. a. Push the wrench—don’t pull toward you b. Pull a wrench—don’t push a wrench 2. The proper term for Channel Locks is ______________. a. Vise Grips b. Crescent wrench c. Locking pliers d. Multigroove adjustable pliers 3. The proper term for Vise Grips is ______________. a. Locking pliers c. Side cuts b. Slip-joint pliers d. Multigroove adjustable pliers 4. Which tool listed is a brand name? a. Locking pliers c. Side cutters b. Monkey wrench d. Vise Grips 5. Two technicians are discussing torque wrenches. Technician A says that a torque wrench is capable of tightening a fastener with more torque than a conventional breaker bar or ratchet. Technician B says that a torque wrench should be calibrated regularly for the most accurate results. Which technician is correct? a. Technician A only b. Technician B only c. Both Technicians A and B d. Neither Technician A nor B

6. What type of screwdriver should be used if there is very limited space above the head of the fastener? a. Offset screwdriver b. Stubby screwdriver c. Impact screwdriver d. Robertson screwdriver 7. Where is the “peen” of the hammer? a. The striking face b. The handle c. The back part opposite the striking face d. The part that connects to the handle 8. What type of hammer is plastic coated, has a metal casing inside, and is filled with small lead balls? a. Dead-blow hammer b. Soft-blow hammer c. Sledge hammer d. Plastic hammer 9. Which type of pliers is capable of fitting over a large object? a. Slip-joint pliers c. Locking pliers b. Linesman’s pliers d. Multigroove adjustable pliers 10. Which tool has a replaceable cutting edge? a. Side-cut pliers c. Utility knife b. Tin snips d. Aviation snips

AIR COMPRESSOR A shop air compressor is usually located in a separate room or an area away from the customer area of a shop. An air compressor is powered by a 220 V AC electric motor and includes a storage tank and the compressor itself, as well as the pressure switches, which are used to maintain a certain minimum level of air pressure in the system. The larger the storage tank, expressed in gallons, the longer an air tool can be operated in the shop without having the compressor start operating. SEE FIGURE 10–1.

SAFE USE OF COMPRESSED AIR

Air under pressure can create dangerous situations. For example, an object, such as a small piece of dirt, could be forced out of an air hose blow gun with enough force to cause serious personal injury. All OSHA-approved air nozzles have air vents drilled around the outside of the main discharge hole to help reduce the force of the air blast. Also, the air pressure used by an air nozzle (blow gun) must be kept to 30 PSI (207 kPa) or less. SEE FIGURE 10–2.

AIR AND ELECTRICALLY OPERATED TOOLS IMPACT WRENCH

An impact wrench, either air (pneumatic) or electrically powered, is a tool that is used to remove and install fasteners. The air-operated 1/2 in. drive impact wrench is the most commonly used unit. SEE FIGURE 10–3. The direction of rotation is controlled by a switch. SEE FIGURE 10–4. Electrically powered impact wrenches commonly include:

Battery-powered units. SEE FIGURE 10–5. 110-volt AC-powered units. This type of impact wrench is very useful, especially if compressed air is not readily available.

CAUTION: Always use impact sockets with impact wrenches, and be sure to wear eye protection in case the socket or fastener shatters. Impact sockets are thicker walled and constructed with premium alloy steel. They are hardened with a black oxide finish to help prevent corrosion and distinguish them from regular sockets. SEE FIGURE 10–6. AIR NOZZLE TRIGGER DISCHARGE TIP NOZZLE

SIDE VENT OPENING

FIGURE 10–1 A typical shop compressor. It is usually placed out of the way, yet accessible to provide for maintenance to the unit.

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AIR HOSE CONNECTOR

FIGURE 10–2 Always use an air nozzle that is OSHA approved. The openings in the side are used to allow air to escape if the nozzle tip were to become clogged.

FIGURE 10–4 This impact wrench features a variable torque setting using a rotary knob. The direction of rotation can be changed by pressing the button at the bottom.

FIGURE 10–6 A black impact socket. Always use impact-type sockets whenever using an impact wrench to avoid the possibility of shattering the socket, which can cause personal injury.

REAL WORLD FIX The Case of the Rusty Air Impact Wrenches In one busy shop, it was noticed by several technicians that water was being pumped through the air compressor lines and out of the vents of air impact wrenches whenever they were used. It is normal for moisture in the air to condense in the air storage tank of an air compressor. One of the routine service procedures is to drain the water from the air compressor. The water had been drained regularly from the air compressor at the rear of the shop, but the problem continued. Then someone remembered that there was a second air compressor mounted over the parts department. No one could remember ever draining the tank from that compressor. After that tank was drained, the problem of water in the lines was solved. The service manager assigned a person to drain the water from both compressors every day and to check the oil level. The oil in the compressor is changed every six months to help ensure long life of the expensive compressors.

FIGURE 10–7 An air ratchet is a very useful tool that allows fast removal and installation of fasteners, especially in areas that are difficult to reach or do not have room enough to move a hand ratchet wrench.

AIR RATCHET

An air ratchet is used to remove and install fasteners that would normally be removed or installed using a ratchet and a socket. An air ratchet is much faster, yet has an air hose attached, which reduces accessibility to certain places. SEE FIGURE 10–7.

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FIGURE 10–8 This typical die grinder surface preparation kit includes the air-operated die grinder, as well as a variety of sanding discs for smoothing surfaces or removing rust.

FIGURE 10–9 A fluorescent trouble light operates cooler and is safer to use in the shop because it is protected against accidental breakage where gasoline or other flammable liquids would happen to come in contact with the light.

WARNING

DIE GRINDER

A die grinder is a commonly used air-powered tool, which can also be used to sand or remove gaskets and rust. SEE FIGURE 10–8.

Do not use incandescent trouble lights around gasoline or other flammable liquids. The liquids can cause the bulb to break and the hot filament can ignite the flammable liquid.

AIR DRILL

An air drill is a drill that rotates faster than electric drills (up to 20,000 RPM). Air drills are commonly used in auto body work when many holes need to be drilled for plug welding.

AIR-BLOW GUN

An air-blow gun is used to clean equipment and other purposes where a stream of air would be needed. Automotive air-blow guns should meet OSHA requirements and include passages to allow air to escape outward at the nozzle, thereby relieving pressure if the nozzle were to become blocked.

AIR-OPERATED GREASE GUN An air-operated grease gun uses shop air to operate a plunger, which then applies a force to the grease cartridge. Most air-operated grease guns use a 1/4 in. air inlet and operate on 90 PSI of air pressure. BATTERY-POWERED GREASE GUN Battery-powered grease guns are more expensive than air-operated grease guns but offer the convenience of not having an air hose attached, making use easier. Many use rechargeable 14 to 18 volt batteries and use standard grease cartridges.

FLUORESCENT A trouble light is an essential piece of shop equipment, and for safety, should be fluorescent rather than incandescent. Incandescent light bulbs can scatter or break if gasoline were to be splashed onto the bulb creating a serious fire hazard. Fluorescent light tubes are not as likely to be broken and are usually protected by a clear plastic enclosure. Trouble lights are usually attached to a retractor, which can hold 20 to 50 ft of electrical cord. SEE FIGURE 10–9. LED TROUBLE LIGHT

Light-emitting diode (LED) trouble lights are excellent to use because they are shock resistant, long lasting, and do not represent a fire hazard. Some trouble lights are battery powered and therefore can be used in places where an attached electrical cord could present problems.

BENCH/PEDESTAL GRINDER A grinder can be mounted on a workbench or on a stand-alone pedestal.

TROUBLE LIGHTS INCANDESCENT

Incandescent lights use a filament that produces light when electric current flows through the bulb. This was the standard trouble light, also called a work light, for many years until safety issues caused most shops to switch to safer fluorescent or LED lights. If incandescent light bulbs are used, try to locate bulbs that are rated “rough service,” which is designed to withstand shock and vibration more than conventional light bulbs.

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BENCH- OR PEDESTAL-MOUNTED GRINDER These high-powered grinders can be equipped with a wire brush wheel and/or a stone wheel.

A wire brush wheel is used to clean steel or sheet metal parts.

A stone wheel is used to grind metal or to remove the mushroom from the top of punches or chisels. SEE FIGURE 10–10.

CAUTION: Always wear a face shield when using a wire wheel or a grinder. Also keep the part support ledge (table), also called a throat plate, within 1/16 inch (2 mm) of the stone.

FIGURE 10–10 A typical pedestal grinder with a wire wheel on the left side and a stone wheel on the right side. Even though this machine is equipped with guards, safety glasses or a face shield should always be worn when using a grinder or wire wheel.

FIGURE 10–12 A hydraulic press is usually used to press bearings on and off on rear axles and transmissions. most vises are serrated and can cause damage to some components unless protected. Many types of protection can be used, including aluminum or copper jaw covers or by simply placing wood between the vise jaws and the component being held. SEE FIGURE 10–11. SAFE USE OF VISES. The jaws of vises can cause damage to the part or component being held. Use pieces of wood or other soft material between the steel jaws and the workpiece to help avoid causing damage. Many vises are sold with optional aluminum jaw covers. When finished using a vise, be sure to close the jaws and place the handle straight up and down to help avoid personal injury to anyone walking near the vise. FIGURE 10–11 A typical vise mounted to a workbench. Most bench grinders are equipped with a grinding wheel (stone) on one side and a wire brush wheel on the other side. A bench grinder is a very useful piece of shop equipment and the wire wheel end can be used for the following:

Cleaning threads of bolts

Cleaning gaskets from sheet metal parts, such as steel valve covers

CAUTION: Only use a steel wire brush on steel or iron components. If a steel wire brush is used on aluminum or copper-based metal parts, it can remove metal from the part. The grinding stone end of the bench grinder can be used for the following:

Sharpening blades and drill bits

Grinding off the heads of rivets or parts

Sharpening sheet metal parts for custom fitting

BENCH VISE A bench vise is used to hold components so that work can be performed on the unit. The size of a vise is determined by the width of the jaws. Two common sizes of vises are 4 in. and 6 in. models. The jaws of

HYDRAULIC PRESSES Hydraulic presses are hand-operated hydraulic cylinders mounted to a stand and designed to press bearings on or off of shafts, as well as other components. To press off a bearing, a unit called a bearing splitter is often required to apply force to the inner race of a bearing. Hydraulic presses use a pressure gauge to show the pressure being applied. Always follow the operating instructions supplied by the manufacturer of the hydraulic press. SEE FIGURE 10–12.

PORTABLE CRANE AND CHAIN HOIST A portable crane is used to remove and install engines and other heavy vehicle components. Most portable cranes use a handoperated hydraulic cylinder to raise and lower a boom that is equipped with a nylon strap or steel chain. At the end of the strap or chain is a steel hook that is used to attach around a bracket or auxiliary lifting device. SEE FIGURE 10–13. SAFE USE OF PORTABLE CRANES. Always be sure to attach the hook(s) of the portable crane to a secure location on the unit being

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FIGURE 10–13 A typical portable crane used to lift and move heavy assemblies, such as engines and transmissions. TECH TIP

FIGURE 10–14 Two engines on engine stands. The plastic bags over the engines help keep dirt from getting onto these engines and engine parts.

Cover Work While Pressing Whenever pressing on a bearing or other component, use an old brake drum over the shaft and the bearing. In the event the bearing shatters during the pressing operation, the brake drum will prevent the parts of the bearing from flying outward where they could cause serious personal injury.

lifted. The hook should also be attached to the center of the weight of the object so it can be lifted straight up without tilting. CAUTION: Always keep feet and other body parts out from underneath the engine or unit being lifted. Always work around a portable crane as if the chain or strap could break at any time.

ENGINE STANDS An engine stand is designed to safely hold an engine and to allow it to be rotated. This allows the technician to easily remove, install, and perform service work to the engine. SEE FIGURE 10–14. Most engine stands are constructed of steel and supported by four casters to allow easy movement. There are two basic places where an engine stand attaches to the engine depending on the size of the engine. For most engines and stands, the retaining bolts attach to the same location as the bell housing at the rear of the engine. On larger engines, such as the 5.9 Cummins inline 6-cylinder diesel engine, the engine mounts to the stand using the engine mounting holes in the block. SEE FIGURE 10–15. SAFE OPERATION OF AN ENGINE STAND. When mounting an engine to an engine stand, be sure that the engine is being supported by a portable crane. Be sure the attaching bolts are grade 5 or 8 and the same thread size as the threaded holes in the block. Check that there is at least 1/2 inch (13 mm) of bolt thread engaged in the threaded holes in the engine block. Be sure that all attaching bolts are securely tightened before releasing the weight of the engine from the crane. Use caution when loosening the rotation retaining bolts because the engine could rotate rapidly, causing personal injury.

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CHAPTER 10

FIGURE 10–15 An engine stand that grasps the engine from the sides rather than the end.

CARE AND MAINTENANCE OF SHOP EQUIPMENT All shop equipment should be maintained in safe working order. Maintenance of shop equipment usually includes the following operations or procedures.

Keep equipment clean. Dirt and grime can attract and hold moisture, which can lead to rust and corrosion. Oil or grease can attract dirt.

Keep equipment lubricated. While many bearings are sealed and do not require lubrication, always check the instructions for the use of the equipment for suggested lubrication and other service procedures.

CAUTION: Always follow the instructions from the equipment manufacturer regarding proper use and care of the equipment.

SETUP AND LIGHTING A TORCH

1

Inspect the cart and make sure the tanks are chained properly before moving it to the work location.

2

Start by attaching the appropriate work tip to the torch handle. The fitting should only be tightened hand tight. Make sure the valves on the torch handle are closed at this time.

3

Each tank has a regulator assembly with two gauges. The high pressure gauge shows tank pressure, and the low pressure gauge indicates working pressure.

4

Open the oxygen tank valve fully, and open the acetylene tank valve 1/2 turn.

5

Open the oxygen valve on the torch handle 1/4 turn in preparation for adjusting oxygen gas pressure.

6

Turn the oxygen regulator valve clockwise and adjust oxygen gas pressure to 20 PSI. Close the oxygen valve on the torch handle.

CONTINUED

PO W E R T O O L S AN D SH OP EQU IP M EN T

87

SETUP AND LIGHTING A TORCH

7

Open the acetylene valve on the torch handle 1/4 turn and adjust acetylene gas pressure to 7 PSI. Close the acetylene valve on the torch handle.

8

9

Put on leather gloves and open the acetylene valve on the torch handle 1/4 turn. Use a flint striker to ignite the acetylene gas exiting the torch tip.

10

Adjust the acetylene valve until the base of the flame just touches the torch tip. Slowly open the oxygen valve on the torch handle and adjust for a neutral flame (blue cone is well-defined).

12

Close the valves on both tanks and turn the regulator handles CCW until they no longer contact the internal springs. Open the gas valves briefly on the torch handle to release gas pressure from the hoses. Close the gas valves on the torch handle and put away the torch assembly.

11

Once work is complete, extinguish the flame by quickly closing the acetylene valve on the torch handle. Be prepared to hear a loud “pop” when the flame goes out. Close the oxygen valve on the torch handle.

88

(CONTINUED)

CHAPTER 10

Open the oxygen valve on the torch handle 1/4 turn and use an appropriate size tip cleaner to clean the tip orifice. Finish by closing the oxygen valve.

HEATING METAL

1

Heating attachments include ordinary heating tips, middle and right and a “rosebud” (left). Ordinary heating tips work fine for most purposes, but occasionally the rosebud is utilized when a great deal of heat is needed.

3

Any time heating or cutting operations are being performed, be sure that any flammables have been removed from the immediate area. A fire blanket may be placed over floor drains or other objects to prevent fires. A fire extinguisher should be on hand in case of an emergency.

5

Note that heating operations should be performed over steel or firebrick. Never heat or cut steel close to concrete, as it could cause the concrete to explode.

2

Note that while acetylene tank pressures are relatively low, the oxygen tank can be filled to over 2,000 PSI. This can represent a serious hazard if precautions are not taken. Be absolutely certain that the tanks are chained properly to the cart before attempting to move it!

4

Be sure to wear appropriate personal protective equipment during heating and cutting operations.

6

When heating steel, move the torch in a circular pattern to prevent melting of the metal. Don’t hold the torch too close to the work as this will cause a “snapping” or “backfire” that can extinguish the flame. CONTINUED

PO W E R T O O L S AN D SH OP EQU IP M EN T

89

CUTTING METAL

7

Affix the cutting attachment to the torch handle. Note that the cutting attachment has a cutting handle and a separate oxygen valve.

9

Oxygen gas pressure should be adjusted to 30 PSI whenever using the cutting attachment. Acetylene pressure is kept at 7 PSI.

11 90

Direct the flame onto a thin spot or sharp edge of the metal to be cut. This will build the heat quicker in order to get the cut started.

CHAPTER 10

8

Fully open the oxygen valve on the torch handle. Oxygen flow will now be controlled with the valve on the cutting attachment.

10

Open the acetylene valve on the torch handle 1/4 turn and light the torch. Adjust the flame until its base just touches the cutting tip. Slowly open the oxygen valve on the cutting attachment and adjust the flame until the blue cone is well-defined.

12

When the metal glows red, depress the cutting handle and move the torch to advance the cut. You will need to move the torch faster when cutting thinner pieces of steel. On thicker pieces, point the cutting tip into the direction of the cut.

REVIEW QUESTIONS 1. List the tools used by service technicians that use compressed air.

3. What safety precautions should be adhered to when working with a vise?

2. Which trouble light design(s) is (are) the recommended type for maximum safety?

4. When using a blow gun, what precautions need to be taken?

CHAPTER QUIZ 1. When using compressed air and a blow gun, what is the maximum allowable air pressure? a. 10 PSI c. 30 PSI b. 20 PSI d. 40 PSI 2. Which air impact drive size is the most commonly used? a. 1/4 in. c. 1/2 in. b. 3/8 in. d. 3/4 in. 3. What type of socket should be used with an air impact wrench? a. Black c. 12 point b. Chrome d. Either a or b 4. What can be used to cover the jaws of a vise to help protect the object being held? a. Aluminum c. Copper b. Wood d. All of the above 5. Technician A says that impact sockets have thicker walls than conventional sockets. Technician B says that impact sockets have a black oxide finish. Which technician is correct? a. Technician A only b. Technician B only c. Both Technicians A and B d. Neither Technician A nor B

chapter

11

6. Two technicians are discussing the use of a typical bench/ pedestal-mounted grinder. Technician A says that a wire brush wheel can be used to clean threads. Technician B says that the grinding stone can be used to clean threads. Which technician is correct? a. Technician A only c. Both Technicians A and B b. Technician B only d. Neither Technician A nor B 7. A hydraulic press is being used to separate a bearing from a shaft. What should be used to cover the bearing during the pressing operation? a. Shop cloth c. Fender cover b. Brake drum d. Paper towel 8. Which type of trouble light is recommended for use in the shop? a. Incandescent c. LED b. Fluorescent d. Either b or c 9. When mounting an engine to an engine stand, what grade of bolt should be used? a. 5 or 8 c. 3 or 5 b. 4 or 7 d. 1 or 4 10. Proper care of shop equipment includes ______________. a. Tuning up every six months b. Keeping equipment clean c. Keeping equipment lubricated d. Both b and c

FLOOR JACK A floor jack is a hand-operated hydraulic device that is used to lift vehicles or components, such as engines, transmissions, and rear axle assemblies. Most floor jacks use four casters, which allow the jack to be easily moved around the shop. SEE FIGURE 11–1.

SAFE USE OF FLOOR JACKS. Floor jacks are used to lift a vehicle or major vehicle component, but they are not designed to hold a load. Therefore safety stands, also called jack stands should always be used to support the vehicle. After the floor jack has lifted the vehicle, safety stands should be placed under the vehicle, and then, using the floor jack, lowered onto the safety stands. The floor jack can be lifted in position as another safety device but the load should be removed from the floor jack. If a load is retained on the floor jack,

FIGURE 11–3 Most newer vehicles have a triangle symbol indicating the recommended hoisting lift points. which lifts the vehicle using hydraulic cylinders. Hoists are rated by the maximum weight that they can safely lift, such as 7,000 to 12,000 or more. Hoists can also have equal length arms or can be equipped with different length arms allowing the vehicle to be set so the doors can be opened and not hit the center support column. Many chassis and underbody service procedures require that the vehicle be hoisted or lifted off the ground. The simplest methods involve the use of drive-on ramps or a floor jack and safety (jack) stands, whereas in ground or surface-mounted lifts provide greater access.

SETTING THE PADS IS A CRITICAL PART OF THIS PROCEDURE All automobile and light-truck service manuals in-

FIGURE 11–2 Safety stands are being used to support the rear of this vehicle. Notice a creeper also. hydraulic fluid can leak past seals in the hydraulic cylinders, which would lower the vehicle, possibly causing personal injury. SEE FIGURE 11–2.

clude recommended locations to be used when hoisting (lifting) a vehicle. Some vehicles have a decal on the driver’s door indicating the recommended lift points. The recommended standards for the lift points and lifting procedures are found in SAE Standard JRP2184. SEE FIGURE 11–3. These recommendations typically include the following points. 1. The vehicle should be centered on the lift or hoist so as not to overload one side or put too much force either forward or rearward. Use tall safety stands if a major component is going to be removed from the vehicle, such as the engine, to help support the vehicle. SEE FIGURE 11–4. 2. The pads of the lift should be spread as far apart as possible to provide a stable platform.

CREEPERS When working underneath a vehicle, most service technicians use a creeper, which consists of a flat or concaved surface equipped with low-profile casters. A creeper allows the technician to maneuver under the vehicle easily.

SAFE USE OF CREEPERS

Creepers can create a fall hazard if left on the floor. When a creeper is not being used, it should be picked up and placed vertically against a wall or tool box to help prevent accidental falls.

VEHICLE HOISTS Vehicle hoists include older in-ground pneumatic/hydraulic (air pressure over hydraulic) and above-ground units. Most of the vehicle hoists used today use an electric motor to pressurize hydraulic fluid,

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3. Each pad should be placed under a portion of the vehicle that is strong and capable of supporting the weight of the vehicle. a. Pinch welds at the bottom edge of the body are generally considered to be strong. CAUTION: Even though pinch weld seams are the recommended location for hoisting many vehicles with unitized bodies (unit-body), care should be taken not to place the pad(s) too far forward or rearward. Incorrect placement of the vehicle on the lift could cause the vehicle to be imbalanced, and the vehicle could fall. This is exactly what happened to the vehicle in FIGURE 11–5. b. Boxed areas of the body are the best places to position the pads on a vehicle without a frame. Be careful to note whether the arms of the lift might come into contact with other parts of the vehicle before the pad touches the intended location. Commonly damaged areas include the following: (1) Rocker panel moldings (2) Exhaust system (including catalytic converter) (3) Tires or body panels. SEE FIGURES 11–6 AND 11–7.

FIGURE 11–5 This training vehicle fell from the hoist when the pads were not set correctly. No one was hurt, but the vehicle was damaged.

(a)

(a)

(b)

FIGURE 11–4 (a) Tall safety stands can be used to provide additional support for a vehicle while on a hoist. (b) A block of wood should be used to avoid the possibility of doing damage to components supported by the stand.

4. As soon as the pads touch the vehicle, check for proper pad placement. The vehicle should be raised about 1 ft (30 cm) off the floor, then stopped and shaken to check for stability. If the vehicle seems to be stable when checked at a short distance from the floor, continue raising the vehicle and continue to view the vehicle until it has reached the desired height. The hoist should be lowered onto the mechanical locks, and then raised off of the locks before lowering. CAUTION: Do not look away from the vehicle while it is being raised (or lowered) on a hoist. Often one side or one end of the hoist can stop or fail, resulting in the vehicle being slanted enough to slip or fall.

(b)

FIGURE 11–6 (a) An assortment of hoist pad adapters that are often necessary to safely hoist many pickup trucks, vans, and sport utility vehicles. (b) A view from underneath a Chevrolet pickup truck showing how the pad extensions are used to attach the hoist lifting pad to contact the frame.

V E H I C L E L I F T I N G A N D H OIS T IN G

93

CHOCK DRIVE-ON RAMPS (a)

FIGURE 11–8 Drive-on-type ramps. The wheels on the ground level must be chocked (blocked) to prevent accidental movement down the ramp.

5. Before lowering the hoist, the safety latch(es) must be released and the direction of the controls reversed. The speed downward is often adjusted to be as slow as possible for additional safety.

DRIVE-ON RAMPS (b)

FIGURE 11–7 (a) In this photo the pad arm is just contacting the rocker panel of the vehicle. (b) This photo shows what can occur if the technician places the pad too far inward underneath the vehicle. The arm of the hoist has dented in the rocket panel.

HINT: Most hoists can be safely placed at any desired height as long as it is high enough for the safety latches to engage. For ease while working, the area in which you are working should be at chest level. When working on brakes or suspension components, it is not necessary to work on them down near the floor or over your head. Raise the hoist so that the components are at chest level.

94

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Ramps are an inexpensive way to raise the front or rear of a vehicle. SEE FIGURE 11–8. Ramps are easy to store, but they can be dangerous because they can “kick out” when driving the vehicle onto the ramps. CAUTION: Professional repair shops do not use ramps because they are dangerous to use. Use only with extreme care.

HOISTING THE VEHICLE

1

The first step in hoisting a vehicle is to properly align the vehicle in the center of the stall.

2

Most vehicles will be correctly positioned when the left front tire is centered on the tire pad.

3

The arms can be moved in and out and most pads can be rotated to allow for many different types of vehicle construction.

4

Most lifts are equipped with short pad extensions that are often necessary to use to allow the pad to contact the frame of a vehicle without causing the arm of the lift to hit and damage parts of the body.

5

Tall pad extensions can also be used to gain access to the frame of a vehicle. This position is needed to safely hoist many pickup trucks, vans, and sport utility vehicles.

6

An additional extension may be necessary to hoist a truck or van equipped with running boards to give the necessary clearance.

CONTINUED

V E H I C L E L I F T I N G A N D H OIS T IN G

95

HOISTING THE VEHICLE

(CONTINUED)

7

Position the pads under the vehicle under the recommended locations.

9

With the vehicle raised one foot (30 cm) off the ground, push down on the vehicle to check to see if it is stable on the pads. If the vehicle rocks, lower the vehicle and reset the pads. The vehicle can be raised to any desired working level. Be sure the safety is engaged before working on or under the vehicle.

11

When the service work is completed, the hoist should be raised slightly and the safety released before using the hydraulic to lower the vehicle.

96

CHAPTER 11

8

After being sure all pads are correctly positioned, use the electromechanical controls to raise the vehicle.

10

If raising a vehicle without a frame, place the flat pads under the pinch weld seam to spread the load. If additional clearance is necessary, the pads can be raised as shown.

12

After lowering the vehicle, be sure all arms of the lift are moved out of the way before driving the vehicle out of the work stall.

REVIEW QUESTIONS 1. Why must safety stands be used after lifting a vehicle with a floor jack?

3. What precautions should be adhered to when hoisting a vehicle?

2. What precautions should be adhered to when storing a creeper?

CHAPTER QUIZ 1. A safety stand is also called a ______________. a. Jack c. Bottle jack b. Jack stand d. Safety stool 2. A creeper should be stored ______________. a. Vertically c. Flat on the floor b. Under a vehicle d. Upside down on the floor 3. The SAE standard for hoist location is ______________. a. J-1980 c. JRP-2184 b. SAE-2009 d. J-14302 4. Tall safety stands would be used to ______________. a. Help support the vehicle when a major component is removed from the vehicle. b. Lift a vehicle c. Lift a component such as an engine high off the ground d. Both b and c 5. Commonly damaged areas of a vehicle during hoisting include ______________. a. Rocker panels c. Tires or body panels b. Exhaust systems d. All of the above 6. Pad extensions may be needed when hoisting what type of vehicle? a. Small cars c. Vans b. Pickup trucks d. Either b or c

chapter

12

7. Technician A says that a hoist can be stopped at any level as long as the safety latch engages. Technician B says that the vehicle should be hoisted to the top of the hoist travel for safety. Which technician is correct? a. Technician A only c. Both Technicians A and B b. Technician B only d. Neither Technician A nor B 8. Before lowering the vehicle, what should the technician do? a. Be sure nothing is underneath the vehicle b. Raise the vehicle enough to release the safety latch c. Be sure no one will be walking under or near the vehicle d. All of the above 9. Technician A says that a creeper should be stored vertically. Technician B says that a creeper should be stored on its casters. Which technician is correct? a. Technician A only c. Both Technicians A and B b. Technician B only d. Neither Technician A nor B 10. When checking for stability, how high should the vehicle be raised? a. About 2 in. (5 cm) c. About 1 ft (30 cm) b. About 6 in. (15 cm) d. About 3 ft (91 cm)

MEASURING SYSTEMS AND TOOLS

OBJECTIVES: After studying Chapter 12, the reader should be able to: • Describe how to read a ruler. • Explain how to use a micrometer and vernier dial caliper. • Describe how to use a telescopic gauge and a micrometer to measure cylinder and lifter bores. • Discuss how to measure valve guides using a small-hole gauge. • Explain how to use feeler gauges and dial indicators. KEY TERMS: Feeler gauge 102 • Sleeve 99 • Small-hole gauge 100 • Spindle 99 • Split-ball gauge 100 • Straightedge 103 • Thickness gauge 102 • Thimble 99

ENGLISH CUSTOMARY MEASURING SYSTEM The English customary measuring system was established about A.D. 1100 in England during the reign of Henry I. The foot was determined to be 12 inches and was taken from the length of a typical foot. The yard

(36 inches) was determined to be the length from King Henry’s nose to the end of his outstretched hand. The mile came from Roman days and was originally defined as the distance traveled by a soldier in 1,000 paces or steps. Other English units, such as the pound (weight) and volume (gallon), evolved over the years from Roman and English measurements. The Fahrenheit temperature scale was created by Gabriel Fahrenheit (1686–1736) and he used 100°F as the temperature of the human body, which he missed by 1.4 degrees (98.6°F is

ME ASU RI N G SYST E M S A N D T OOL S

97

?

FREQUENTLY ASKED QUESTION

What Weighs a Gram?

3/16

To better understand the metric system measurements, it is often helpful to visualize a certain object and relate it to a metric unit of measure. For example, the following objects weigh about 1 gram.

1/16

• A dollar bill • A small paper clip

7/16 5/16

11/16 9/16

3/8

1/8 1/4

15/16

13/16

5/8

7/8 3/4

1/2

1

considered now to be normal temperature). On the Fahrenheit scale, water freezes at 32°F and water boils at 212°F.

METRIC SYSTEM OF MEASURE Most of the world uses the metric system of measure. The metric system was created in the late 1700s in France and used the physical world for the basis of the measurements. For example, the meter was defined as being 1/40,000,000 of the circumference of the earth (the distance around the earth at the poles). The Celsius temperature scale developed by Anders Celsius (1701–1744) used the freezing point of water as 0°C (32°F) and the boiling point of water as 100°C (212°F). Other units include a liter of water, which was then used as a standard of weight where 1 liter of water (about 1 quart) weighs 1 kilogram (1,000 grams). Units of measure are then divided or multiplied by 10, 100, and 1,000 to arrive at usable measurements. For example, a kilometer is 1,000 meters and is the most commonly used metric measurement for distance for travel. Other prefixes include:

1

2

FIGURE 12–1 A rule showing that the larger the division, the longer the line.

All units of measure, except for the base units, are a combination of units that are referred to as derived units of measure. Some examples of derived units include:

1 inch 1/2 inch 1/4 inch

Torque

1/8 inch

Velocity

1/16 inch

Density Energy Power

98

A tape measure or machinist rule divides inches into smaller units. Each smaller unit is drawn with a line shorter than the longer unit. The units of measure starting with the largest include:

CHAPTER 12

Some rules show 1/32 of an inch. SEE FIGURE 12–1. A metric scale is also included on many tape measures and machinists rules. SEE FIGURE 12–2.

CRANKSHAFT MEASUREMENT

Even though the connecting rod journals and the main bearing journals are usually different sizes, they both can and should be measured for out-of-round and taper. SEE FIGURE 12–7.

MICROMETER A micrometer is the most used measuring instrument in engine service and repair. SEE FIGURE 12–3. The thimble rotates over the sleeve on a screw that has 40 threads per inch. Every revolution of the thimble moves the spindle 0.025 in. The thimble is graduated into 25 equally spaced lines; therefore, each line represents 0.001 in. Every micrometer should be checked for calibration on a regular basis. SEE FIGURES 12–4 THROUGH 12–6.

OUT-OF-ROUND. A journal should be measured in at least two positions across the diameter and every 120 degrees around the journal, as shown in FIGURE 12–8, for an example of the six readings. Calculate the out-of-round measurement by subtracting the lowest reading from the highest reading for both A and B positions. Position A: 2.0000 ⫺ 1.9995 ⫽ 0.0005 in. Position B: 2.0000 ⫺ 1.9989 ⫽ 0.0011 in.

MEASURING FACES

The maximum out-of-round measurement occurs in position B (0.0011 in.), which is the measurement that should be used to compare against factory specifications to determine if any machining will be necessary.

SPINDLE ANVIL

LOCK NUT SLEEVE 0

TAPER. To determine the taper of the journal, compare the readings in the same place between A and B positions and subtract the lower reading from the higher reading. For example:

5

1

0

THIMBLE

Position A

RATCHET STOP

FIGURE 12–3 A typical micrometer showing the names of the parts. The sleeve may also be called the barrel or stock.

Position B

2.0000

⫺

2.0000

⫽ 0.0000

1.9999

⫺

1.9999

⫽ 0.0000

1.9995

⫺

1.9989

⫽ 0.0006

Use 0.0006 in. as the taper for the journal and compare with factory specifications.

GAUGE ROD 0

0

CAMSHAFT MEASUREMENT The journal of the camshaft(s) can also be measured using a micrometer and compared with factory specifications for taper and out-of-round. SEE FIGURE 12–9. NOTE: On overhead valve (pushrod) engines, the camshaft journal diameter often decreases slightly toward the rear of the engine. Overhead camshaft engines usually have the same journal diameter.

FIGURE 12–4 All micrometers should be checked and calibrated as needed using a gauge rod.

0.0212 INCH (a)

0.0775 INCH (b)

0.5280 INCH (c)

FIGURE 12–5 The three micrometer readings are (a) 0.0212 in.; (b) 0.0775 in.; (c) 0.5280 in. These measurements used the vernier scale on the sleeve to arrive at the ten-thousandth measurement. The number that is aligned represents the digit in the ten-thousandth place. ME ASU RI N G SYST E M S A N D T OOL S

99

0.187 MM

3.601 MM

(a)

5.5350 MM

(b)

(c)

FIGURE 12–6 Metric micrometer readings that use the vernier scale on the sleeve to read to the nearest 0.001 millimeter. The arrows point to the final reading for each of the three examples.

120°

120°

120°

FIGURE 12–9 Camshaft journals should be measured in three locations, 120 degrees apart, to check for out-of-round. The cam lift can also be measured with a micrometer and compared with factory specifications, as shown in FIGURE 12–10. 0

1

5

0

TELESCOPIC GAUGE

FIGURE 12–7 Using a micrometer to measure the connecting rod journal for out-of-round and taper.

2.0000"

2.0000" 1.9999"

120° 120° A

B

120° A

CHAPTER 12

Camshaft bearing ( SEE FIGURE 12–12.)

Main bearing bore (housing bore) measurement

Connecting rod bore measurement

1.9999" 120° 120°

1.9995"

120°

1.9989"

SMALL-HOLE GAUGE

B

FIGURE 12–8 Crankshaft journal measurements. Each journal should be measured in at least six locations, but also in position A and position B and at 120-degree intervals around the journal.

100

A telescopic gauge is used with a micrometer to measure the inside diameter of a hole or bore. The cylinder bore can be measured by inserting a telescopic gauge into the bore and rotating the handle lock to allow the arms of the gauge to contact the inside bore of the cylinder. Tighten the handle lock and remove the gauge from the cylinder. Use a micrometer to measure the telescopic gauge. SEE FIGURE 12–11. A telescopic gauge can also be used to measure the following:

A small-hole gauge (also called a split-ball gauge) is used with a micrometer to measure the inside diameter of small holes such as a valve guide in a cylinder head. SEE FIGURES 12–13 AND 12–14.

0

1

5

0

(a)

FIGURE 12–10 Checking a camshaft for wear by measuring the lobe height with a micrometer.

TELESCOPIC GAUGE

OUTSIDE MICROMETER (b)

FIGURE 12–12 (a) A telescopic gauge being used to measure the inside diameter (ID) of a camshaft bearing. (b) An outside micrometer used to measure the telescopic gauge.

(a)

?

FREQUENTLY ASKED QUESTION

What Is the Difference Between the Word Gage and Gauge? The word gauge means “measurement or dimension to a standard of reference.” The word gauge can also be spelled gage. Therefore, in most cases, the words mean the same.

(b)

FIGURE 12–11 When the head is first removed, the cylinder taper and out-of-round should be checked below the ridge (a) and above the piston when it is at the bottom of the stroke (b).

INTERESTING NOTE: One vehicle manufacturing representative told me that gage was used rather than gauge because even though it is the second acceptable spelling of the word, it is correct and it saved the company a lot of money in printing costs because the word gage has one less letter! One letter multiplied by millions of vehicles with gauges on the dash and the word gauge used in service manuals adds up to a big savings to the manufacturer.

ME ASU RI N G SYST E M S A N D T OOL S

101

DIAL

KNIFE EDGE JAWS TO MEASURE INSIDE DIAMETERS

ROD USED TO MEASURE DEPTH OF RECESSES

BLADE

OUTSIDE JAWS USED TO MEASURE OUTSIDE DIAMETERS

(a) EACH SMALL LINE IS EQUAL TO 0.002"

80 70

FIGURE 12–13 Cutaway of a valve guide with a hole gauge adjusted to the hole diameter.

90 0 10

20 30 40

60

4 5 6 7 8 9

5"

5

1 2 3 4 5

50

50

40

60

30 20

70 10 0 90

80

0.5"

ADD READING ON BLADE (5.5") TO READING ON DIAL (0.036") TO GET FINAL TOTAL MEASUREMENT (5.536")

(b) 0

1

5

0

FIGURE 12–15 (a) A typical vernier dial caliper. This is a very useful measuring tool for automotive engine work because it is capable of measuring inside, outside, and depth measurements. (b) To read a vernier dial caliper, simply add the reading on the blade to the reading on the dial.

FIGURE 12–14 The outside of a hole gauge being measured with a micrometer.

VERNIER DIAL CALIPER A vernier dial caliper is normally used to measure length, inside and outside diameters, and depth. SEE FIGURE 12–15.

FIGURE 12–16 A group of feeler gauges (also known as thickness gauges), used to measure between two parts. The long gauges on the bottom are used to measure the piston-to-cylinder wall clearance.

FEELER GAUGE A feeler gauge (also known as a thickness gauge) is an accurately manufactured strip of metal that is used to determine the gap or clearance between two components. SEE FIGURE 12–16.

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A feeler gauge can be used to check the following:

Piston ring gap ( SEE FIGURE 12–17.)

Piston ring side clearance

Connecting rod side clearance

Piston-to-wall clearance

FEELER GAUGE

DIAL INDICATOR

PISTON RING

FIGURE 12–17 A feeler gauge, also called a thickness gauge, is used to measure the small clearances such as the end gap of a piston ring.

FIGURE 12–19 A dial indicator is used to measure valve lift during flow testing of a high-performance cylinder head.

FIGURE 12–18 A straightedge is used with a feeler gauge to determine if a cylinder head is warped or twisted.

STRAIGHTEDGE A straightedge is a precision ground metal measuring gauge that is used to check the flatness of engine components when used with a feeler gauge. A straightedge is used to check the flatness of the following:

Cylinder heads ( SEE FIGURE 12–18.)

Cylinder block deck

Straightness of the main bearing bores (saddles)

DIAL INDICATOR A dial indicator is a precision measuring instrument used to measure crankshaft end play, crankshaft runout, and valve guide wear. A dial indicator can be mounted three ways, including:

Magnetic mount. This is a very useful method because a dial indicator can be attached to any steel or cast iron part.

FIGURE 12–20 A dial bore gauge is used to measure cylinders and other engine parts for out-of-round and taper conditions.

Clamp mount. A clamp-mounted dial indicator is used in many places where a mount could be clamped.

Threaded rod. Using a threaded rod allows the dial indicator to be securely mounted, such as shown in FIGURE 12–19.

DIAL BORE GAUGE A dial bore gauge is an expensive, but important, gauge used to measure cylinder taper and out-of-round as well as main bearing (block housing) bore for taper and out-of-round. SEE FIGURE 12–20. A dial bore gauge has to be adjusted to a dimension, such as the factory specifications. The reading on the dial bore gauge then indicates plus (⫹) or minus (⫺) readings from the predetermined dimension. This is

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why a dial bore is best used to measure taper and out-of-round because it shows the difference in cylinder or bore rather than an actual measurement.

DEPTH MICROMETER A depth micrometer is similar to a conventional micrometer except that it is designed to measure the depth from a flat surface. SEE FIGURE 12–21. FIGURE 12–21 A depth micrometer being used to measure the height of the rotor of an oil pump from the surface of the housing.

REVIEW QUESTIONS 1. Explain how a micrometer is read. 2. Describe how to check a crankshaft journal for out-of-round and taper. 3. List engine components that can be measured with the help of a telescopic gauge.

4. List the gaps or clearances that can be measured using a feeler (thickness) gauge. 5. Explain why a dial bore gauge has to be set to a dimension before using.

CHAPTER QUIZ 1. The threaded movable part that rotates on a micrometer is called the ______________. a. Sleeve b. Thimble c. Spindle d. Anvil

6. Which of the following cannot be measured using a feeler gauge? a. Valve guide clearance b. Piston-ring gap c. Piston-ring side clearance d. Connecting rod side clearance

2. To check a crankshaft journal for taper, the journal should be measured in at least how many locations? a. One b. Two c. Four d. Six

7. Which of the following cannot be measured using a straightedge and a feeler gauge? a. Cylinder head flatness b. Block deck flatness c. Straightness of the main bearing bores d. Straightness of the cylinder bore

3. To check a crankshaft journal for out-of-round, the journal should be measured in at least how many locations? a. Two b. Four c. Six d. Eight

SCIENTIFIC METHOD The scientific method is a series of steps taken to solve a problem. These steps help eliminate errors and to achieve an accurate result. The scientific method is the foundation of automotive diagnosis. A scientific method involves the following steps: STEP 1

Observe the conditions or problem and define or describe the problem.

STEP 2

Formulate an explanation that could be the cause of the problem.

STEP 3

Use the explanation (hypothesis) to test to see if it matches the existing problem. If not, then return to step 2 to formulate another explanation.

STEP 4

After the explanation has proved to be a possible solution to a problem, additional tests should be performed to verify that the method works all of the time.

USING THE SCIENTIFIC METHOD While a service technician will not perform research, using a scientific approach to problem solving is very important. This means that every fault should be investigated to determine the root cause rather than solving what at first is thought to be the problem or fault. The root cause is the true cause of a failure, which may not be noticed at first. Many service technicians ask themselves “why” when they discover a fault. Often this leads to another possible problem and then the technician should ask another “why.” This scientific method of finding the root cause of an automotive problem is often called the “five whys.” By the time the technician has asked “why” five times, the root cause is usually discovered. EXAMPLES OF THE FIVE WHYS As an example of using a scientific method approach to automotive faults, an owner may state that the vehicle does not start and the battery appears to be dead. Therefore, applying the five whys (scientific approach) first ask why:

First why—What caused the battery to become discharged? To answer this question requires observation and the creating

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1 FOOT

10 POUNDS

HEAT AND LIGHT

MECHANICAL

FIGURE 13–2 Torque is a twisting force equal to the distance from the pivot point times the force applied expressed in units called pound-feet (lb-ft) or Newton-meters (N-m).

10 FEET 100 LBS

CHEMICAL

SOUND

FIGURE 13–1 Energy, which is the ability to perform work, exists in many forms.

of a hypothesis, such as “is the battery defective” or “did the customer leave the lights on?” This requires questioning the owner and testing the battery.

Second why—Assume that the battery was in good condition but discharged. Now the technician should ask the second why. “Why did the battery become discharged?” This means that a battery ignition off drain test needs to be performed as well as testing of the charging system. Assume the battery drain test was okay, but that the charging system was not working properly.

Third why—The charging system was found to be not working correctly. A visual inspection found that the alternator drive belt was not tight enough to properly operate the alternator. The technician needs to ask the third why, “Why is the accessory drive belt still loose?”

Fourth why—“Why was the accessory drive belt loose?” The cause could be a defective tensioner. If the tensioner itself was not a problem, then another “why” needs to be asked.

Fifth why—If the accessory belt and belt tensioner were okay, then further investigation would be needed to find the root cause. For example, “Is one of the tensioner retaining bolts loose, maybe from a previous repair?” This could be the root cause.

FIGURE 13–3 Work is calculated by multiplying force times distance. If you push 100 pounds 10 feet, you have done 1,000 foot-pounds of work. to useful energy, such as the potential energy stored in a battery or a vehicle at the top of a hill. In both of these cases, there is no energy being released but if the battery were connected to an electrical load, such as a light bulb, or the vehicle starts moving down the hill, the energy is being released.

TORQUE Torque is the term used to describe a rotating force that may or may not result in motion. Torque is measured as the amount of force multiplied by the length of the lever through which it acts. If a one-foot-long wrench is used to apply 10 pounds of force to the end of the wrench to turn a bolt, then 10 pound-feet of torque is being applied. SEE FIGURE 13–2. The metric unit for torque is Newton-meters because Newton is the metric unit for force and the distance is expressed in meters. 1 pound-foot ⫽ 1.3558 Newton-meters 1 Newton-meter ⫽ 0.7376 pound-foot

WORK ENERGY PRINCIPLES Energy is the ability or the capacity to do work. There are many forms of energy, but chemical, mechanical, and electrical energy are the most familiar kinds involved in the operation of an automobile. SEE FIGURE 13–1. Energy in the form of a moving object is called kinetic energy. An example of kinetic energy is a moving vehicle. Energy is called potential energy if it is capable of being changed

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Work is defined as actually accomplishing movement when force (torque) is applied to an object. A service technician can apply torque to a bolt in an attempt to loosen it, yet no work is done until the bolt actually moves. Work is calculated by multiplying the applied force (in pounds) by the distance the object moves (in feet). If you applied 100 pounds of force to move an object 10 feet, then you accomplished 1,000 foot-pounds of work (100 pounds ⫻ 10 feet ⫽ 1,000 foot pounds). SEE FIGURE 13–3.

What Is the Difference between Torque and Work? The designations for torque and work are often confusing. Torque is expressed in pound-feet because it represents a force exerted a certain distance from the object and acts as a lever. Work, however, is expressed in footpounds because work is the movement over a certain distance (feet) multiplied by the force applied (pounds). Engines produce torque and service technicians exert torque represented by the unit pound-feet.

POWER The term power means the rate of doing work. Power equals work divided by time. Work is achieved when a certain amount of mass (weight) is moved a certain distance by a force. If the object is moved in 10 seconds or 10 minutes does not make a difference in the amount of work accomplished, but it does affect the amount of power needed. Power is expressed in units of foot-pounds per minute.

165 FEET (50 M) 165 FEET (50 M) PER MINUTE

FIGURE 13–4 One horsepower is equal to 33,000 foot-pounds (200 lbs ⫻ 165 ft) of work per minute.

HORSEPOWER The power an engine produces is called horsepower (hp). One horsepower is the power required to move 550 pounds one foot in one second, or 33,000 pounds one foot in one minute (550 lb ⫻ 60 sec ⫽ 33,000 lb). This is expressed as 500 foot-pounds (ft-lb) per second or 33,000 foot-pounds per minute. SEE FIGURE 13–4. The actual horsepower produced by an engine is measured with a dynamometer. A dynamometer (often abbreviated as dyno

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or dyn) places a load on the engine and measures the amount of twisting force the engine crankshaft places against the load. The load holds the engine speed, so it is called a brake. The horsepower derived from a dynamometer is called brake horsepower (bhp). The dynamometer actually measures the torque output of the engine. Torque is a rotating force that may or may not cause movement. The horsepower is calculated from the torque readings at various engine speeds (in revolutions per minute or RPM). Horsepower is torque times RPM divided by 5252. Torque ⫻ RPM Horsepower ⫽ 5252

3,000 LB

= 90,301 FT-LB

30 MPH

= 180,602 FT-LB

6,000 LB 30 MPH

Torque is what the driver “feels” as the vehicle is being accelerated. A small engine operating at a high RPM may have the same horsepower as a large engine operating at a low RPM.

FIGURE 13–5 Kinetic energy increases in direct proportion to the weight of the vehicle.

NOTE: As can be seen by the formula for horsepower, the higher the engine speed for a given amount of torque, the greater the horsepower.

Engineers calculate kinetic energy using the following formula:

NEWTON’S LAWS OF MOTION Sir Isaac Newton (1643–1727) was an English physicist and mathematician who developed many theories of science, including three laws of motion. 1. Newton’s first law of motion states that an object at rest tends to stay at rest and an object in motion tends to stay in motion unless acted on by an outside force. For example, it requires a large force to get a vehicle that is stopped into motion. It also requires that a force be applied to slow and stop a vehicle that is in motion. 2. Newton’s second law of motion states that the force needed to move an object is proportional to the mass of the object multiplied by the acceleration rate of the object. This means that it requires a great deal more force to accelerate a heavy sport utility vehicle (SUV) than a small economy vehicle. The rate of acceleration also depends on the amount of force that is applied. 3. Newton’s third law of motion states that for every action, there is an opposite and equal reaction. For example, when the airfuel mixture is ignited in an engine, the force is exerted on the piston, which is forced downward, which causes the crankshaft of the engine to rotate. The opposite action is applied to the cylinder head of the engine and applies the same force although this part is designed not to move.

KINETIC ENERGY Kinetic energy is a fundamental form of mechanical energy. It is the energy of mass in motion. Every moving object possesses kinetic energy, and the amount of that energy is determined by the object’s mass and speed. The greater the mass of an object and the faster it moves, the more kinetic energy it possesses. Even at low speeds, a moving vehicle has enough kinetic energy to cause serious injury and damage. The job of the brake system is to dispose of that energy in a safe and controlled manner.

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2

mv ⫽ Ek 29.9 where: m ⫽ mass or weight of the vehicle in pounds v ⫽ velocity of the vehicle in miles per hour Ek ⫽ kinetic energy in foot-pounds (ft-lb) Another way to express this equation is as follows. weight ⫻ speed 29.9

2

⫽ kinetic energy

If a 3,000-pound vehicle traveling at 30 mph is compared to a 6,000-pound vehicle also traveling at 30 mph as shown in FIGURE 13–5, the equations for computing their respective kinetic energies look like this: 2

3,000 lb ⫻ 30 mph ⫽ 90,301 ft-lb 29.9 2

6,000 lb ⫻ 30 mph ⫽ 180,602 ft-lb 29.9 The results show that when the weight of a vehicle is doubled from 3,000 to 6,000 pounds, its kinetic energy is also doubled from 90,301 foot-pounds to 180,602 foot-pounds. In mathematical terms, kinetic energy increases proportionally as weight increases. In other words, if the weight of a moving object doubles, its kinetic energy also doubles. If the weight quadruples, the kinetic energy becomes four times as great. If a 3,000-pound vehicle traveling at 30 mph is compared to the same vehicle traveling at 60 mph ( FIGURE 13–6), the equations for computing their respective kinetic energies look like this: 2

3,000 lb ⫻ 30 mph ⫽ 90,301 ft-lb 29.9 2

3,000 lb ⫻ 60 mph ⫽ 361,204 ft-lb 29.9 The results show that the vehicle traveling at 30 mph has over 90,000 foot-pounds of kinetic energy, but at 60 mph the figure increases to over 350,000 foot-pounds. In fact, at twice the speed, the vehicle has exactly four times as much kinetic energy. If the speed were doubled again to 120 mph, the amount of kinetic energy

1 FT 3,000 LB

2 FT

= 90,301 FT-LB

30 MPH

5-LB FORCE

FULCRUM

3,000 LB

= 361,204 FT-LB

60 MPH

10-LB WEIGHT

FIGURE 13–7 A first-class lever increases force and changes the direction of the force.

FIGURE 13–6 Kinetic energy increases as the square of any increase in vehicle speed.

?

LEVER

1½ FT

1½ FT

FREQUENTLY ASKED QUESTION

What Is the Difference Between Mass and Weight? Mass is the amount of matter in an object. One of the properties of mass is inertia. Inertia is the resistance to being put in motion and the tendency to remain in motion once it is set in motion. The weight of an object is the force of gravity on the object and may be defined as the mass times the acceleration of gravity. Therefore, mass means the property of an object and weight is a force.

TECH TIP

5-LB FORCE

FULCRUM 10-LB WEIGHT

LEVER

FIGURE 13–8 A second-class lever increases force in the same direction as it is applied.

process and the selection of brake components. Inertia is defined by Isaac Newton’s first law of motion, which states that a body at rest tends to remain at rest, and a body in motion tends to remain in motion in a straight line unless acted upon by an outside force.

MECHANICAL PRINCIPLES

Brakes Cannot Overcome the Laws of Physics No vehicle can stop on a dime. The energy required to slow or stop a vehicle must be absorbed by the braking system. All drivers should be aware of this fact and drive at a reasonable speed for the road and traffic conditions.

would grow to almost 1,500,000 foot-pounds! In mathematical terms, kinetic energy increases as the square of its speed. In other words, if the speed of a moving object doubles (2), the kinetic energy becomes four times as great (22 ⫽ 4). And if the speed quadruples (4), say from 15 to 60 mph, the kinetic energy becomes 16 times as great (42 ⫽ 16). This is the reason speed has such an impact on kinetic energy.

KINETIC ENERGY AND BRAKE DESIGN

The relationships between weight, speed, and kinetic energy have significant practical consequences for the brake system engineer. If vehicle A weighs twice as much as vehicle B, it needs a brake system that is twice as powerful. But if vehicle C has twice the speed potential of vehicle D, it needs brakes that are, not twice, but four times more powerful.

INERTIA Although brake engineers take both weight and speed capability into account when designing a brake system, these are not the only factors involved. Another physical property, inertia, also affects the braking

The primary mechanical principle used to increase application force in every brake system is leverage. In the science of mechanics, a lever is a simple machine that consists of a rigid object, typically a metal bar that pivots about a fixed point called a fulcrum. There are three basic types of levers, but the job of all three is to change a quantity of energy into a more useful form. A first-class lever increases the force applied to it and also changes the direction of the force. SEE FIGURE 13–7. With a first-class lever, the weight is placed at one end while the lifting force is applied to the other. The fulcrum is positioned at some point in between. If the fulcrum is placed twice as far from the long end of the lever as from the short end, a 10-pound weight on the short end can be lifted by only a 5-pound force at the long end. However, the short end of the lever will travel only half as far as the long end. Moving the fulcrum closer to the weight will further reduce the force required to lift it, but it will also decrease the distance the weight is moved. A second-class lever increases the force applied to it and passes it along in the same direction. SEE FIGURE 13–8. With a second-class lever, the fulcrum is located at one end while the lifting force is applied at the other. The weight is positioned at some point in between. If a 10-pound weight is placed at the center of the lever, it can be lifted by only a 5-pound force at the end of the lever. However, the weight will only travel half the distance the end of the lever does. As the weight is moved closer to the fulcrum, the force required to lift it, and the distance it travels, are both reduced. A third-class lever actually reduces the force applied to it, but the resulting force moves farther and faster. SEE FIGURE 13–9.

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1½ FT

MASTER CYLINDER

1½ FT

FULCRUM

FULCRUM LEVER

20-LB FORCE

2 IN. 10-LB WEIGHT

50-LB FORCE

FIGURE 13–9 A third-class lever reduces force but increases the speed and travel of the resulting work.

With a third-class lever, the fulcrum is located at one end and the weight is placed at the other. The lifting force is applied at some point in between. If a 10-pound weight is placed at the end of the lever, it can be lifted by a 20-pound force applied at the middle of the lever. Although the force required to move the weight has doubled, the weight is moved twice as far and twice as fast as the point on the lever where the force was applied. The closer to the fulcrum the lifting force is applied, the greater the force required by the weight and the farther and faster the weight will move. The levers in brake systems are used to increase force, so they are either first- or second-class. Second-class levers are the most common, and the service brake pedal is a good example. In a typical suspended brake pedal, the pedal arm is the lever, the pivot point is the fulcrum, and the force is applied at the foot pedal pad. SEE FIGURE 13–10. The force applied to the master cylinder by the pedal pushrod attached to the pivot is much greater than the force applied at the pedal pad, but the pushrod does not travel nearly as far. Leverage creates a mechanical advantage that, at the brake pedal, is called the pedal ratio. For example, a pedal ratio of 5 to 1 is common for manual brakes, which means that a force of 10 pounds at the brake pedal will result in a force of 50 pounds at the pedal pushrod. In practice, leverage is used at many points in both the service and parking brake systems to increase braking force while making it easier for the driver to control the amount of force applied.

10 IN.

LEVER 10-LB FORCE

FIGURE 13–10 This brake pedal assembly provides a 5:1 mechanical advantage because a 10-lb force input results in a 50-lb force into the master cylinder.

TECH TIP Conductors and Insulators If a material is a good conductor of heat, it is also a good conductor of electricity. Most conductors are metals, such as steel, copper, aluminum, and brass. Most insulators are nonmetals, such as plastic and rubber. Therefore, if a material does not conduct heat, it usually will not conduct electricity.

?

FREQUENTLY ASKED QUESTION

How Does a Coat Keep You Warm? A coat is worn in cold weather to keep warm. Does it keep the cold out or the heat in? Actually, both, but because heat travels from a warm object (human body) to a colder object (outside cold air), the primary purpose of a coat is to keep the body heat from escaping into the cold air.

HEAT AND TEMPERATURE Heat and temperature are related but are not the same. Temperature is the intensity of the heat source, whereas heat is the quantity of heat. For example, the heat from a match and a large fire may measure the same temperature, but the amount of heat generated by the fire is far greater than the amount of heat generated by a single match.

HEAT Heat is measured in units called British Thermal Units, abbreviated BTUs. One BTU is the amount of heat needed to raise the temperature of one pound of water one degree Fahrenheit. For example, room heaters and air conditioners are rated in how many BTUs per hour can be added (heater) or removed (air conditioner) from a space in one hour. Heat energy can be transferred by three ways, including:

Conduction—Conduction is the process of the heat traveling from a hotter part to a colder part of the same object or by direct contact. For example, if one end of a steel bar is heated, then the heat will travel by conduction toward the colder areas of the bar. Also, if the metal were touched, heat would travel from the steel bar to the finger. Metals are good conductors of heat, whereas plastic, rubber, and ceramics are poor conductors of heat and are called insulators.

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Convection—Convection is the transfer of heat through a liquid or a gas, which causes it to rise while the cooler liquid or gas falls within a container. A hot air balloon is an example where hot gas in the balloon causes it to rise above the surrounding cooler air.

Radiation—Radiation is a method of energy transfer where heat is transmitted through the air. Heat from the sun is transmitted through the atmosphere where it heats the ground. Heat can be felt above a hot stove.

TEMPERATURE

Temperature is the measurement of the ability to give up or absorb heat from another body. Heat always flows from a warmer object to a colder object. Temperature is measured using two scales: 1. Celsius (also called centigrade). The Celsius scale was devised by taking the freezing point and the boiling point of water and dividing it into 100 equal parts.

?

FREQUENTLY ASKED QUESTION

What Is Thermodynamics? Thermodynamics is the study of the relationship among temperature, pressure, and volume changes. The laws of thermodynamics help engineers design and develop engines with higher efficiency. Thermodynamics is therefore used in the design of the cooling system, as well as in the engine, because the more heat created by the burning of fuel in the engine, the more power the engine can develop using the same or less amount of fuel.

?

FIGURE 13–11 A typical outdoor thermometer which is used to measure temperature, not heat.

Can Water and Acid Be Mixed Together? Acids have a very strong affinity for water and as a result, if water is poured into acid, the resulting reaction would be extremely violent and acid would be forced outward in all directions. Always pour acid into water, never water into acid. Technicians seldom need to work with acids because even battery electrolytes from the water and acid are premixed to help prevent the possibility of a technician creating a harmful reaction.

TECH TIP Quick and Easy Temperature Conversion Many service information and scan tool data are expressed in degrees Celsius, which is often confusing to those used to temperature expressed in Fahrenheit degrees. A quick and easy way to get an approximate conversion is to take the degrees in Celsius, double it, and add 25. For example, Celsius ⫻ 2 ⫹ 25 ⫽ approximate Fahrenheit degrees:

2. Fahrenheit. The Fahrenheit scale was developed by Gabriel Fahrenheit (1686–1736), a German physicist who proposed the scale in 1724. He wanted to avoid using negative numbers, so the scale used had zero degrees representing the coldest outside air temperature he had ever measured and used his own body temperature to represent 100 degrees. Later, more accurate measurements indicate that average human body temperature to be 98.6 degrees so he was off by 1.4 degrees. Also, negative outside air temperatures can occur. SEE FIGURE 13–11 and the comparison chart. Temperature Symbol

Degree Celsius °C

Degree Fahrenheit °F

Boiling point of water

100.0

212.0

Average human body temperature

37.0

98.6

Average room temperature

20.0 to 25.0

68.0 to 77.0

Melting point of ice

0.0

32.0

ACIDS Acids are substances that can corrode metals and some can cause severe burns to the skin. Common household acids that are not harmful and taste sour include vinegar and lemon juice (citric acid). Stronger acids include:

Hydrochloric acid

Nitric acid

Battery acid

BASES A base is a substance that can also burn the skin if strong enough and is also referred to as alkaline. Common household bases are generally not harmful unless eaten and have a bitter taste, including baking soda, soap, and antacid, such as Milk of Magnesia®. Stronger bases, which can burn the skin include:

Lye (sodium hydroxide)

Bleach

Drain cleaner

pH SCALE

Most chemical cleaners used for cleaning carbontype deposits are a strong soap, or caustic material. A value called pH, measured on a scale from 1 to 14, is used to indicate the amount of chemical activity. The term pH is from the French word pouvoir hydrogine, meaning “hydrogen power.” Pure water is neutral. On the pH scale, water is pH 7. Caustic materials have pH numbers from 8 through 14. The higher the number, the stronger the caustic action will be. Acid materials have pH numbers from 6 through 1. The lower the number, the stronger the acid action will be. Caustic materials and acid materials neutralize each other, such as when baking soda (a caustic) is used to clean the outside of the battery

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(an acid surface). The caustic baking soda neutralizes any sulfuric acid that has been spilled or splashed on the outside of the battery.

TECH TIP

CAUTION: Whenever working with chemicals, eye protection must be used.

Wear Hearing Protection According to audiologists (hearing and speech doctors), a person should wear ear protection if the level of sound requires that your voice be raised in order to be heard. Any level that exceeds 90 dB requires the use of ear protection to avoid hearing loss. This means that ear protection should be worn when using a power mower or using an air tool, such as an air impact wrench or air ratchet.

GAS LAWS Gas laws are a set of characteristics that describe how gases act and the relationship between their temperature, pressure, and volume. Gas laws have application in most systems of the vehicle, including tires, air-conditioning systems, and anywhere else gases are present.

BOYLE’S LAW

Boyle’s law was first written in 1662 by Robert Boyle (1627–1691) and describes the relationship between volume and pressure of a gas in a closed container. Boyle’s law states that the volume of a gas varies inversely (opposite) with the pressure exerted against it in a closed container. Therefore, if a closed container is compressed, the volume of the gas inside is reduced but the pressure is increased.

CHARLES’S LAW Charles’s Law was first formulated about 1787 by a French scientist, Jacque Charles (1746–1823). According to Charles’s law when the temperature of a gas increases, the volume increases. When the temperature of a gas decreases, the volume decreases.

SOUND AND ACOUSTICS Sound is the movement of air which the ear interprets as sound. Sound travels through the air, which is called propagation. Propagation of sound is normally thought to be only transmitted through air, but liquids can also transmit sound waves. Sound has two properties:

Frequency. This is also called the pitch of the sound and is measured in Hertz or cycles per second. Normal hearing frequency ranges from as low as 20 Hertz to 20,000 Hertz. Very low frequencies, such as the heart beat, of one or two Hertz cannot be heard. High frequencies over 20,000 Hertz also cannot be detected by humans.

Intensity. The intensity of sound, which is also called loudness, is measured in decibels (dB) named for Alexander Graham Bell (1847–1922), the inventor of the telephone. Relative intensity (loudness), using the decibel scale, includes the following examples:

Whisper

10–20 dB

Normal conversation

60 dB

Thunder

110 dB

Threshold of pain

120 dB

ACOUSTICS Acoustics is the study of sound and how it is generated and transmitted. Acoustic engineers are employed by vehicle manufacturers to help reduce noise and designing methods to reduce or stop the noise from being transmitted into the passenger compartment. For example, according to acoustic engineers, about 80% of the noise created by the movement of the tires on the road is transmitted through the chassis and body of the vehicle. Only about 20% of the sound is transferred to the passenger compartment through the air.

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PLASTICS There are two basic types of plastic.

THERMOSET PLASTIC

This type of plastic is changed chemically when cured and shaped and cannot be reheated or reformed. Rubber is an example of a thermoset plastic material that cannot be remelted and reformed after curing. Other examples of thermoset plastics include:

Bakelite (phenol formaldehyde resin)

Polyester resin

Epoxy resin

THERMOPLASTIC This type of plastic is flexible at room temperature. Thermoplastic can be recycled by grinding it into pieces and remolding it into another shape. Examples of thermoplastics include:

Polyethylene (PE)

Polyvinyl chloride (PVC)

Polystyrene (PS)

ABS (acrylonitrile butadiene styrene)

PA nylon (polyamides)

PLASTIC IDENTIFICATION While it is not important for the average service technician to determine what kind of plastic is being used for what application, it is important to know when restoring a part or refinishing a plastic part. For example, interior plastic parts can be made from the following plastic material:

Polypropylene plastic (PP)

Polyethylene (PE) ( SEE FIGURE 13–12)

ABS plastic

ABS/PVC plastic

Vinyl (PVC) plastic

Most large plastic pieces are labeled on the inside with letters, such as PP or PE. However, if no marking is visible, it is still possible to identify the type of plastic using a simple basic test. A painter will need to know the type of plastic if refinishing these parts. Often replacement plastic parts are available in only one color and must be painted to match the original when being replaced. A burn test is used to test if the plastic part is polypropylene or ABS plastic by performing the following steps: STEP 1

Remove a small piece from a hidden back side of the plastic part being tested.

STEP 2

Hold the small piece of plastic with tweezers and ignite the plastic.

STEP 3

Observe the burning of the plastic: • No visible smoke means that the plastic is polypropylene. • Visible black smoke means that the plastic is ABS.

of carbon is 0.01%. In other words, 100 points of carbon is equal to 1%. The percentage of carbon in steel has a huge input on the strength and characteristics of the steel. For example,

FIGURE 13–12 This interior plastic part is labeled PE-HD, which means polyethylene-high density.

STEP 4

To determine if a part to be painted is polyvinyl chloride, a copper wire test needs to be performed by heating a copper wire and then touching the heated wire to a hidden back side surface of the part being tested. After melting some plastic onto the copper wire, return the wire to the flame and observe the color of the flame. If the color of the flame is green/ blue or turquoise, then the plastic is polyvinyl chloride (vinyl).

After the type of plastic has been identified, then check with service information and paint literature to determine the proper paint and preparations needed to refinish the plastic part.

IRON AND STEEL Iron is a chemical element with a symbol of Fe. It is one of the most commonly available elements on earth and is refined from iron ore. Steel is made from iron after further refining. The main difference between iron and steel is the amount of carbon. The amount of carbon is critical to the strength and characteristics of iron and steel.

CAST IRON

Cast iron contains carbon is usually in the shape of 0.004 inches long. Cast iron is used tions, including engine blocks, rear suspension components.

2% to 4% carbon and this flakes of graphite 0.001 to in many automotive applicaaxle assemblies, and some

DUCTILE CAST IRON

In ductile iron, the carbon in the alloy with silicon are small ball-shapes called spherloidols. Ductile iron is also called malleable iron and is used to make crankshafts.

GRAY CAST IRON

Gray cast iron is cast iron that has another element, silicon, in the alloy giving the metal a gray color. Gray cast iron is used for engine blocks. NOTE: Cast iron contains graphite, which acts as a lubricant when being machined. As a result, cooling oil or water is not needed when making cast iron brake rotors or brake drums.

SAE STEEL DESIGNATIONS Steels are designed by a system established by the Society of Automotive Engineers and includes numbers to indicate the main element used in the alloy, plus the “points of carbon.” One part

Mild (low carbon) steel has less than 20 points of carbon (0.02%). Mild steel is soft and easily formed but is not very strong. Common usage of low carbon steel is in tables and chairs and vehicle body parts where strength is not an issue.

Medium carbon steel usually has between 25 and 50 points of carbon (0.25% and 0.50%). This type of steel can be heat treated to create steel that is ductile (flexible) and yet has good strength. This type of steel is usually used in forgings and machined components.

High carbon steel usually has between 60 and 100 points (0.60% and 1.00%) of carbon and is very strong. It is commonly used in vehicle springs and can be hardened. CAUTION: Both medium carbon and high carbon steel can be hardened by heating and then cooling, using water or oil to rapidly cool the metal. Therefore, if heating any metal, always allow it to cool slowly to avoid changing the hardness of the steel. The SAE numbering designation usually includes four numbers:

The first two numbers indicate the type of alloy which could include several alloy elements.

A commonly used alloy for forged crankshafts is SAE 4340. The analysis of this designation is: 4340 ⫽ An alloy that contains 1.82% nickel, 0.5% to 0.8% chromium, and 0.25% molybdenum with 40 points of carbon.

ALUMINUM AND ALUMINUM ALLOYS Aluminum is a lightweight metal that is used in many automotive applications, including suspension components, engine blocks, and cylinder heads. Aluminum is almost always combined with small quantities of other metals to form an alloy, using copper, manganese, zinc, or silicon. Aluminum and aluminum alloys that are mechanical shaped are called wrought alloys and are labeled according to the International Alloy Designation system. The system uses a four-digit number, which identifies the alloying elements, followed by a dash (-) and then a letter identifying the type of heat treatment. This is followed by a number identifying the specific hardness or temper of the finished alloy. A typical example would be 6061-T6. The 6061 is a 6000 series alloy with magnesium and silicon. The “61” further identifies other elements and their percentages. The numbering system for cast aluminum alloy is similar but is designed by standards of the Aluminum Association (AA). SC I E N T I F I C PRI N C I PL E S A N D M A T ERIA L S

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REVIEW QUESTIONS 1. What is kinetic energy?

4. How can a burn test help identify the type of plastic used?

2. How is mechanical advantage used in the braking system?

5. What is the pH of acids and bases?

3. What is the difference between torque and power?

CHAPTER QUIZ 1. All of the following are correct statements about braking except: a. Kinetic energy must be absorbed by the braking system. b. Kinetic energy of a vehicle doubles when the speed doubles. c. The heavier the vehicle, the greater the kinetic energy when moving. d. If the vehicle weight is doubled, the kinetic energy of a moving vehicle is doubled. 2. The brake pedal assembly uses a mechanical lever to ______________. a. Increase the driver’s force on the brake pedal applied to the master cylinder. b. Decrease the distance the brake pedal needs to be depressed by the driver. c. Decrease the driver’s force on the brake pedal applied to the master cylinder. d. Allow for clearance between the brake pedal and the floor when the brakes are applied.

5. An example of a lever and mechanical advantage used on a vehicle is the ______________. a. Radio volume control c. Fuel tank b. Brake pedal d. Battery 6. Two technicians are discussing temperature and heat. Technician A says that temperature is the intensity of the heat source. Technician B says that heat is the amount of heat. Which technician is correct? a. Technician A only c. Both Technicians A and B b. Technician B only d. Neither Technician A nor B 7. Heat can move or travel by ______________. a. Conduction c. Radiation b. Convection d. All of the above 8. Technician A says that zero degrees Celsius is the freezing temperature of water. Technician B says that 100 degrees Celsius is the boiling temperature of water. Which technician is correct? a. Technician A only c. Both Technicians A and B b. Technician B only d. Neither Technician A nor B

3. Technician A says that work is being performed if a force is being applied, yet the object does not move. Technician B says that torque is a twisting force that may or may not result in motion. Which technician is correct? a. Technician A only c. Both Technicians A and B b. Technician B only d. Neither Technician A nor B

9. Technician A says that pure (distilled) water has a pH of 7. Technician B says that the pH of acids is less than 7. Which technician is correct? a. Technician A only c. Both Technicians A and B b. Technician B only d. Neither Technician A nor B

4. Two technicians are discussing engine horsepower and torque figures. Technician A says that torque is measured on a dynamometer. Technician B says that horsepower is measured on a dynamometer. Which technician is correct? a. Technician A only c. Both Technicians A and B b. Technician B only d. Neither Technician A nor B

10. Technician A says that the kinetic energy of a vehicle is proportional to its weight. Technician B says that the kinetic energy of a moving vehicle is directly proportional to its speed. Which technician is correct? a. Technician A only c. Both Technicians A and B b. Technician B only d. Neither Technician A nor B

DECIMALS Decimals are commonly used by service technicians. The placement of the decimal point indicates the value of the number. The naming of decimals includes tenths, hundredths, thousandths, and higher. Decimals are used to represent fractions of a unit by using a dot called a decimal point to indicate that the number is a decimal.

TENTHS A decimal with one number to the right of the decimal point indicates an accuracy of 1/10 or 0.1. For example, 0.7 is the same as 7/10 and is pronounced “seven tenths” or “zero point seven.” A decimal can also include numbers larger than zero, but has a resolution or accuracy measured in tenths, such as in 14.7.

VALVE CLEARANCE

CAM LOBE HEEL

ADJUSTING SHIM

CAM FOLLOWER

FIGURE 14–1 Valve clearance allows the metal parts to expand and maintain proper operation, both when the engine is cold or at normal operating temperature. Adjustment is achieved by changing the thickness of the adjusting shim.

HUNDREDTH

Decimals with two numbers to the right of the decimal point indicate an accuracy to 1/100 or 0.01. For example, 0.47 is pronounced “forty-seven hundredth” or “zero point four seven.”

THOUSANDTH A decimal with three numbers to the right of the decimal point indicates an accuracy to 1/1000 or 0.001. For example, 0.867 is pronounced “eight hundred sixty-seven thousandth” or “zero point eight six seven.” ADDING AND SUBTRACTING DECIMALS When adding or subtracting decimals, the decimal point has to be aligned. This ensures that the numbers are placed into the correct position of tenth, hundredth, and thousandth. For example: 0.147 ⫹ 0.02 0.167 Notice that the top number is expressed in thousandths and the lower number is expressed in hundredths. The final figure is also shown in thousandths. NOTE: If these numbers were measurements, the first result cannot be more accurate than the least accurate measurement. This means that the final result should be expressed in hundredths instead of thousandths. When subtracting or multiplying decimals, keep the decimal points aligned or use a calculator making certain to include the decimal point.

PERCENTAGE Percentage is the relationship of a value or number out of 100. Using money as an example, three quarters (25 cents each) equals 75 cents ($0.75) or 75% of a dollar ($1.00). Many examples are not that easy, for example, 70 is what percentage of 120? To determine the percentage, divide the first number (70) by the second number (120). 70 120 0.58 To convert this number to a percentage, multiply the number by 100 or move the decimal point two places to the right (58) and then add a percentage symbol to indicate that the number is a percentage (58%).

SCIENTIFIC NOTATION Very large and very small decimal numbers are frequently expressed using scientific notation. Scientific notation is written as a number multiplied by the number of zeros to the right or left of the decimal point. For example, 68,000 could be written as 6.8 ⫻ 104, indicating that the number shown has 3 zeros plus the 8 to the right of the decimal point. Small numbers, such as 0.00068, would use a negative sign beside the number over the 10 to represent that the decimal point needs to be moved toward the left (6.8 ⫻ 10⫺4).

ADDING AND SUBTRACTING Technicians are often required to add or subtract measurements when working on vehicles. For example, adding and subtracting is needed to select shims (thin pieces of steel) for adjusting valve clearance or differential preload measurements. For example, if the valve clearance specification is 0.012 in. and the clearance is actually 0.016 in., and the shim that is in place between the camshaft lobe and the valve bucket is 0.080 in. thick, what size (thickness) of shim needs to be installed to achieve the correct valve clearance? Solution: The shim thickness of 0.080 in. results in a valve clearance of 0.016 in. The specification requires that the shim needs to be thicker to reduce the valve clearance. SEE FIGURE 14–1. To determine the thickness of a shim, the amount of clearance needed to be corrected needs to be calculated. The original clearance is 0.016 in. and the specification is 0.012 in. The difference is determined by subtracting the actual clearance from the specified clearance: 0.016 0.012 0.004 in. The result (0.004 in.) then needs to be added to the thickness of the existing shim to determine the thickness of the replacement shim needed to achieve the correct valve clearance. Existing shim thickness 0.080 in. Additional thickness needed 0.004 in. Thickness of new shim 0.084 in.

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?

FRACTIONS

FREQUENTLY ASKED QUESTION

How Is Metric Fuel Economy Measured? Fractions, such as 1/2, 1/4, or 5/8 are commonly found in specifications for hose inside diameter measurements. A tape measure or machinists rule can be used to measure the fitting or the original part. Sometimes, fractions need to be converted to decimal units if the replacement parts are offered by that measurement method. When comparing fractions to decimal units, think about the number of cents in a dollar. 1/2 dollar ⫽ 50 cents

In the United States fuel economy is expressed in miles per gallon. Outside of the United States, fuel economy is measured in the number of liters of fuel needed to travel 100 kilometers (62 miles), abbreviated L/100 km. This means that as the number increases, the fuel economy decreases. For example: MPG

L/100 km

5

47.0

1/10 (dime) ⫽ 10 cents

10

23.5

1/20 (nickel) ⫽ 5 cents

15

15.7

20

11.8

25

9.4

Quarter ⫽ 25 cents

Other fractions, such as 3/8, 5/8, and 5/16 are harder to determine. If a chart is not available, divide the bottom number, called the denominator into the top number, called the numerator.

30

7.8

3/8 ⫽ 3 divided by 8 ⫽ 0.375

35

6.7

5/8 ⫽ 5 divided by 8 ⫽ 0.625

40

5.9

45

5.2

50

4.7

5/16 ⫽ 5 divided by 16 ⫽ 0.3125

MULTIPLYING AND DIVIDING Multiplying by a service technician is usually done to determine gear ratios and to determine the total of many of the same items. For example, the final overall gear ratio is determined by multiplying the transmission gear ratio by the final drive ratio and is covered later in this chapter. Dividing is commonly done when calculating total resistance of many resistances connected in parallel. In this situation, the value of the resistance is divided by the number of equal resistances. For example, if four bulbs with a resistance of 0.4 ohm were connected in parallel, the total resistance would be just 0.1 ohm (0.4 ⫼ 4 ⫽ 0.1).

In the metric system, the fuel is measured; in the United States, the miles are measured.

Replacing the terms with the actual numbers results in the following: RPM

5668 70 2.41 336 2180 RPM 26 26

FUEL ECONOMY CALCULATOR MATHEMATICAL FORMULAS A formula uses letters to represent values or measurements and indicates how these numbers are to be multiplied, divided, added, or subtracted. To use a formula, the technician needs to replace the letters with the actual number and perform the indicated math functions. For example, a formula used to determine engine speed in revolutions per minute (RPM) and is represented by the following formula: RPM

To calculate fuel economy in miles per gallons, two factors must be known: 1. How far was the vehicle driven. 2. How many gallons of fuel were needed. This calculation requires that the fuel tank be filled two times; first at the start of the test and then at the end of the test distance. For example: STEP 1

Fill the tank until the nozzle clicks off. NOTE: Try to use the same station and pump, if possible, to achieve the most accurate results.

mph gear ratio 336 tire diameter (inches)

This formula is used to determine the speed of the engine compared to the gear ratio and tire size. Sometimes, wheel and tire sizes are changed and knowing this is helpful. To calculate the engine speed, the actual information needs to be placed into the formula.

STEP 2

Drive a reasonable distance. For the example, 220 miles were traveled.

STEP 3

Fill the fuel tank and record the number of gallons used. For this example, exactly 10.0 gallons were needed to refill the tank.

Mph 70 mph Gear ratio 2:41:1 Tire diameter 26 inches

STEP 4

Calculate fuel economy: MPG ⫽ Miles driven divided by the number of gallons used.

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MPG 220 divided by 10.0 22.0 miles per gallon

24 TEETH

24 TEETH

8 TEETH

8 TEETH

DRIVE GEAR DRIVEN GEAR

FIGURE 14–2 The drive gear is attached or is closer to the power source and rotates or drives the driven gear.

DRIVEN GEAR

DRIVE GEAR

FIGURE 14–3 If the driven gear is rotating faster than the drive gear, it is called an overdrive ratio. MAX TORQUE = 153.0

MAX. POWER = 170.9

Direct drive

Gear reduction

Overdrive

DIRECT DRIVE

If two meshed gears are the same size and have the same number of teeth, they will turn at the same speed. Since the drive gear turns once for each revolution of the driven gear, the gear ratio is 1:1; this is called a direct drive. When a transmission is in direct drive, the engine and transmission turn at the same speed.

GEAR REDUCTION

If one gear drives a second gear that has three times the number of teeth, the smaller drive gear must travel three complete revolutions in order to drive the larger gear through one rotation. SEE FIGURE 14–2. Divide the number of teeth on the driven gear by the number of teeth on the drive gear and you get a 3:1 gear ratio (pronounced three to one). This type of gear arrangement, where driven gear speed is slower than drive gear speed, provides gear reduction. Gear reduction may also be called underdrive as drive speed is less than, or under, driven speed. Both terms mean the same thing and use is a matter of preference. Gear reduction is used for the lower gears in a transmission. First gear in a transmission is called “low” gear because output speed, not gear ratio, is low. Low gears have numerically high gear ratios. That is, a 3:1 gear ratio is a lower gear than those with a 2:1 or 1:1 gear ratio. These three ratios taken in order represent a typical upshift pattern from low gear (3:1), to second gear (2:1), to third gear (1:1).

OVERDRIVE Overdrive is the opposite of a gear reduction condition and occurs when a driven gear turns faster than its drive gear. For the gears shown in FIGURE 14–3, the driven gear turns three times for each turn of the drive gear. The driven gear is said to overdrive the drive gear. For this example, the gear ratio is 0.33:1.

175

150

150

125

125

100

100

75

75

50 20

SAE TORQUE (FT-LBS)

When one gear turns another, the speed that the two gears turn in relation to each other is the gear ratio. Gear ratio is expressed as the number of rotations the drive gear must make in order to rotate the driven gear through one revolution. To obtain a gear ratio, simply divide the number of teeth on the driven gear by the number of teeth on the drive gear. Gear ratios, which are expressed relative to the number one, fall into three categories:

SAE HORSEPOWER

GEAR RATIOS

175

50 30

50 40 RPM (X100)

60

70

FIGURE 14–4 A graph showing horsepower and torque. Notice that the curves cross at 5252 RPM or a little bit to the right of the 50, which is expressed as the graph number multiplied by 100. Example is 52 multiplied by 100 equals 5200 RPM. The torque and horsepower curves cross at 5252 RPM because torque is measured by a dynamometer and then horsepower is calculated using a formula which causes both values to be the same at that one engine speed. Overdrive ratios of 0.65:1 and 0.70:1 are typical of those used in automotive applications. NOTE: Ratios always end in 1 with a colon in between. Therefore, the first number is less than 1 if it is an overdrive ratio and greater than 1 if it is a gear reduction ratio.

GRAPHS, CHARTS, AND DIAGRAMS GRAPH READING

A graph is a visual display of information. Graphs are commonly used in the automotive service industry to illustrate trends or specifications along with time or some other variable. A variable is a measurement of something that changes, such as engine speed or time. A graph has two variables displayed. One variable changes from left to right on the horizontal axis. This is called the X axis. The other variable is displayed on the vertical axis, called the Y axis. A graph is created by making a series of dots at various locations and then connecting the dots with a line. SEE FIGURE 14–4.

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RANGE

FORWARD CLUTCH

FORWARD SPRAG CL. ASSEMBLY

FIRST GEAR

APPLIED

HOLDING

SECOND GEAR APPLIED

APPLIED

HOLDING

THIRD GEAR

APPLIED

HOLDING

GEAR

2–4 BAND

REVERSE OVERRUN INPUT CLUTCH CLUTCH

3–4 CLUTCH

LO-ROLLER CLUTCH

LO-REV. CLUTCH

PARKNEUTRAL HOLDING

OVERDRIVE FOURTH GEAR

APPLIED

APPLIED

APPLIED

FIRST GEAR

APPLIED

APPLIED

HOLDING

SECOND GEAR APPLIED

APPLIED

APPLIED

HOLDING

THIRD GEAR

APPLIED

APPLIED

HOLDING

FIRST GEAR

APPLIED

APPLIED

HOLDING

SECOND GEAR APPLIED

APPLIED

APPLIED

HOLDING

MANUAL 1ST

FIRST GEAR

APPLIED

REVERSE

REVERSE

DRIVE

MANUAL 2ND

APPLIED

HOLDING

APPLIED

HOLDING

APPLIED

HOLDING

HOLDING

APPLIED APPLIED

FIGURE 14–5 A typical chart showing what is applied in what gear in an automatic transmission. INTERPRETING A GRAPH. To interpret a graph, select a point along the horizontal axis (X axis) and then look directly above the point where the line appears. Mark this spot and then look directly to the left along the vertical axis (Y axis) to see what value is represented by the points on the graph.

CHART READING A chart is used to represent data, such as numbers or specifications, along with another variable, such as model or year of vehicle. A chart is very useful for showing many different specifications or other facts in an easy-to-read format. SEE FIGURE 14–5 for an example of a transmission specifications chart, which shows the transmission parts listed along the horizontal axis (X axis) and gear of the automatic transmission along the vertical or Y axis. INTERPRETING A CHART. A chart can look complicated but if studied, it is easy to interpret. Start by looking along the horizontal or vertical axis for the information, such as the range of the transmission down the left column. Then look to the right to find which device is being used to achieve that transmission drive range.

DIAGRAM READING A diagram is a graphic design that explains or shows the arrangement of parts. Diagrams are commonly used in the automotive service industry to show how a component is assembled and in which order the parts are placed together. SEE FIGURE 14–6 for an example. INTERPRETING A DIAGRAM A diagram usually shows the relationship of many parts. Lines are used to show the centerline of the part and the identity of the part is often shown as a number or letter. A separate chart or area of the diagram needs to be looked at to determine the name of the part. Diagrams are most helpful when disassembling or assembling a component, such as a transmission.

FIGURE 14–6 An exploded view showing how the thermostat is placed in the engine.

For best results, use electronic information and print out the diagram so it can be written on and can be thrown away when the repair has been completed. This process also helps prevent getting grease on the pages of a service manual.

REVIEW QUESTIONS 1. What is the formula for determining fuel economy? 2. Why are the torque and horsepower of an engine equal at 5252 RPM? 3. What service operation may require the technician to add and subtract?

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4. What service operation may require the technician to multiply or divide? 5. How is fuel economy expressed in the metric system? 6. What math function is needed to calculate the overall gear ratio if the transmission and differential ratios are both known?

Vehicle Service Information, Identification, and Routine Maintenance 17 Preventative Maintenance and Service Procedures

15 Service Information 16 Vehicle Identification and Emission Ratings

chapter

SERVICE INFORMATION

15 OBJECTIVES: After studying Chapter 15, the reader should be able to: • Discuss the importance of vehicle history. • Retrieve vehicle service information. • Read and interpret service manuals and electronic service information. • Describe the use of the vehicle owner’s manual. KEY TERMS: Julian date 123 • Labor guides 122 • Service information 120 • Technical service bulletin (TSB) 122

SE RV I C E IN F ORM A T ION

119

REAL WORLD FIX Owner’s Manual Is the Key to Proper Operation A customer purchased a used Pontiac Vibe and complained to a shop that the cruise control would disengage and had to be reset if driven below 25 mph (40 km/h). The service technician was able to verify that in fact this occurred, but did not know if this feature was normal or not. The technician checked the owner’s manual and discovered that this vehicle was designed to operate this way. Unlike other cruise control systems, those systems on Toyota-based vehicles are designed to shut off below 25 mph, requiring the driver to reset the desired speed. The customer was informed that nothing could be done to correct this concern and the technician also learned something. Vehicles that use the Toyota cruise control system include all Toyotas, plus Lexus, Pontiac Vibe, and Chevrolet Prism.

FIGURE 15–1 The owner’s manual has a lot of information pertaining to the operation as well as the maintenance and resetting procedures that technicians often need.

VEHICLE SERVICE HISTORY RECORDS Whenever service work is performed, a record of what was done is usually kept on file by the shop or service department for a number of years. The wise service technician will check the vehicle service history if working on a vehicle with an unusual problem. Often, a previous repair may indicate the reason for the current problem or it could be related to the same circuit or components. For example, a collision could have caused hidden damage that can affect the operation of the vehicle. Knowing that a collision had been recently repaired may be helpful to the technician.

OWNER’S MANUALS It has been said by many automotive professional technicians and service advisors that the owner’s manual is not read by many vehicle owners. Most owner’s manuals contain all or most of the following information.

HINT: Some vehicle manufacturers offer owner’s manuals on their website for a free download.

SERVICE MANUALS Factory and aftermarket service manuals, also called shop manuals, contain specifications and service procedures. While factory service manuals cover just one year and one or more models of the same vehicle, most aftermarket service manuals cover multiple years and/ or models in one manual. Included in most service manuals are the following:

Capacities and recommended specifications for all fluids

Specifications including engine and routine maintenance items

Testing procedures

Service procedures including the use of special tools when needed

Component location information

1. How to reset the maintenance reminder light 2. Specifications, including viscosity of oil needed and number of quarts (liters) 3. Tire pressures and standard as well as optional tire sizes 4. Maintenance schedule for all fluids, including coolant, brake fluid, automatic transmission fluid, and differential fluid 5. How to program the remote control as well as the power windows and door locks 6. How to reset the tire pressure monitoring system after a tire rotation

SEE FIGURE 15–1

LUBRICATION GUIDES Lubrication guides, such as those published by Chek-Chart and Chilton, include all specifications for lubrication-related service including:

While some factory service manuals are printed in one volume, most factory service information is printed in several volumes due to the amount and depth of information presented. The typical factory service manual is divided into sections.

Exploded views of components such as engines and transmissions are available in shop manuals and electronic service information, as well as in parts and labor time guides. These views, showing all of the parts as if the assembly was blown apart, give the service technician a clear view of the various parts and their relationship to other parts in the assembly.

It is often a benefit to have the written instructions or schematics (wiring diagrams) at the vehicle while diagnosing or performing a repair. One advantage of a hard copy service manual is that it can be taken to the vehicle and used as needed. However, dirty hands can often cause pages to become unreadable. The advantage of electronic format service information is that the material can be printed out and taken to the vehicle for easy access. This also allows the service technician to write or draw on the printed copy, which can be a big help when performing tests such as electrical system measurements. These notes can then be used to document the test results on the work order.

MAINTENANCE

AND

LUBRICATION

INFORMATION

Maintenance and lubrication information includes topics such as:

Schedule for “normal” as well as “severe” usage time and mileage charts

TECH TIP Look for Severe Service Times Many time guides provide additional time for vehicles that may be excessively rusted due to climate conditions or have been subjected to abuse. Be sure to quote the higher rate if any of these conditions are present on the customer’s vehicle.

ADVANTAGES OF HARD COPY VERSUS ELECTRONIC SERVICE INFORMATION All forms of service information have some advantages, including: Hard Copy • Easy to use—no hardware or expensive computers needed • Can be taken to the vehicle for reference • Can view several pages easily for reference

FIGURE 15–2 Some technical service bulletins also include the designated flat-rate time when specifying a repair procedure.

Electronic Service Information • Information can be printed out and taken to the vehicle • Has a search function for information • Internet or network access allows use at several locations in the shop

DISADVANTGES OF HARD COPY VERSUS ELECTRONIC SERVICE INFORMATION All forms of service information have some disadvantages, including:

ELECTRONIC SERVICE INFORMATION There are many programs available that will provide electronic service information for the automotive industry. Sometimes the vehicle makers make information available on CDs or DVDs, but mostly it is available online. Most electronic service information has technical service bulletins (TSBs), wiring diagrams and a main menu that includes the major components of the vehicle as a starting point. SEE FIGURE 15–3. ALLDATA and Mitchell On-Demand are commonly used software programs that include service information for many vehicles. Service information and testing procedures should be closely followed including any symptom charts or flow charts. A sample of a symptom information chart is shown CHART 15–1.

Hard Copy

Electronic Service Information

HOME SCREEN The Home screen is the first screen displayed when you start. It displays buttons that represent the major sections of the program. Access to the Home screen is available from anywhere within the program by clicking the Home button on the toolbar.

• Can be lost or left in the vehicle

• Requires a computer and printer

TOOLBARS

• Cost is high for each manual

• Internet or network access can be a challenge

• Can get dirty and unreadable

• Cost can be high

LABOR GUIDE MANUALS Labor guides, also called flat-rate manuals, list vehicle service procedures and the time it should take an average technician to complete the task. This flat-rate time is then the basis for estimates and pay for technicians. Some manuals also include a parts list, including the price of the part to help service advisors create complete estimates for both labor and parts. These manuals are usually called “parts and time guides.” Some guides include labor time only. SEE FIGURE 15–2.

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A main toolbar is displayed on most screens, providing quick access to certain functions. This toolbar varies somewhat, depending upon what information is being accessed.

ELECTRONIC SERVICE INFORMATION Electronic service information is available mostly by subscription and provides access to an Internet site where service manual–type information is available. Most vehicle manufacturers also offer electronic service information to their dealers and to most schools and colleges that offer corporate training programs. TECHNICAL SERVICE BULLETINS Technical service bulletins, often abbreviated TSBs, are issued by the vehicle manufacturer to notify service technicians of a problem and include the necessary corrective action. Technical service bulletins are designed for dealership technicians but are republished by aftermarket companies and made available along with other service information to shops and vehicle repair facilities.

INTERNET The Internet has opened the field for information exchange and access to technical advice. One of the most useful websites is the International Automotive Technician’s network at www.iatn.net. This is a free site but service technicians need to register to join. For a small monthly sponsor fee, the shop or service

technician can gain access to the archives, which include thousands of successful repairs in the searchable database.

RECALLS AND CAMPAIGNS

A recall or campaign is issued by a vehicle manufacturer and a notice is sent to all owners in the event of a safety- or emission-related fault or concern. While these faults may be repaired by independent shops, it is generally handled by a local dealer. Items that have created recalls in the past have included potential fuel system leakage problems, exhaust leakage, or electrical malfunctions that could cause a possible fire or the engine to stall. Unlike technical service bulletins whose cost is only covered when the vehicle is within the warranty period, a recall or campaign is always done at no cost to the vehicle owner.

?

FREQUENTLY ASKED QUESTION

What Is the Julian Date?

FIGURE 15–3 A main menu showing the major systems of the vehicle. Clicking on one of these major topics opens up another menu showing more detailed information.

The Julian date (abbreviated JD) is the number of the day of the year. January 1 is day 001. The Julian date is named for Julius Caesar, who developed the current calendar. The Julian date is often mentioned in technical service bulletin where changes need to be made to certain component if the date of manufactured falls within the specified Julian dates.

POSSIBLE CAUSE

REASON

Throttle-position (TP) sensor

• The TP sensor should be within the specified range at idle. If too high or too low, the computer may not provide a strong enough extra pulse to prevent a hesitation. • An open or short in the TP sensor can result in hesitation because the computer would not be receiving correct information regarding the position of the throttle.

Throttle-plate deposit buildup

An airflow restriction at the throttle plates creates not only less air reaching the engine but also swirling air due to the deposits. This swirling or uneven airflow can cause an uneven air-fuel mixture being supplied to the engine, causing poor idle quality and a sag or hesitation during acceleration.

Manifold absolute pressure (MAP) sensor fault

The MAP sensor detects changes in engine load and signals to the computer to increase the amount of fuel needed for proper operation. Check the vacuum hose and the sensor itself for proper operation.

Check the throttle linkage for binding

A kinked throttle cable or cruise (speed) control cable can cause the accelerator pedal to bind.

Contaminated fuel

Fuel contaminated with excessive amounts of alcohol or water can cause a hesitation or sag during acceleration. HINT: To easily check for the presence of alcohol in gasoline, simply get a sample of the fuel and place it in a clean container. Add some water and shake. If no alcohol is in the gasoline, the water will settle to the bottom and be clear. If there is alcohol in the gasoline, the alcohol will absorb the water. The alcohol-water combination will settle to the bottom of the container, but will be cloudy rather than clear.

Clogged, shorted, or leaking fuel injectors

Any injector problem that results in less than an ideal amount of fuel being delivered to the cylinders can result in a hesitation, a sag, or stumble during acceleration.

Spark plugs or spark plug wires

Any fault in the ignition system such as a defective spark plug wire or cracked spark plug can cause hesitation, a sag, or stumble during acceleration. At higher engine speeds, a defective spark plug wire is not as noticeable as it is at lower speeds, especially in vehicles equipped with a V-8 engine.

EGR valve operation

Hesitation, a sag, or stumble can occur if the EGR valve opens too soon or is stuck partially open.

False air

A loose or cracked intake hose between the mass airflow (MAF) sensor and the throttle plate can be the cause of hesitation.

CHART 15–1 A chart showing symptoms for hesitation while accelerating. These charts help the technician diagnose faults that do not set a diagnostic trouble code (DTC).

SE RV I C E IN F ORM A T ION

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TECH TIP Use a Bluetooth Hands-Free Telephone When talking to a hotline service provider, it is wise to be looking at the vehicle during the call to be able to provide information about the vehicle and perform the suggested tests. This makes the job of troubleshooting easier and faster for both the technician and the service provider, resulting in shorter length calls. Using a Bluetooth hands-free telephone should help shorten the length of calls, which means the cost will be less for the help service.

FIGURE 15–4 Whenever calling a hot line service be sure that you have all of the vehicle information ready and are prepared to give answers regarding voltage readings or scan tool data when talking to the vehicle specialist.

HOTLINE SERVICES A hotline service provider is a subscription-based helpline to assist service technicians solve technical problems. While services vary, most charge a monthly fee for a certain amount of time each month to talk to an experienced service technician who has a large amount of resource materials available for reference. Often, the technician hired by the hotline services specializes in one vehicle make and is familiar with many of the pattern failures that are seen by other technicians in the field. Hotline services are an efficient way to get information on an as-needed basis. Some examples of hotline automotive service providers include:

AFTERMARKET SUPPLIES GUIDES AND CATALOGS Aftermarket supplies guides and catalogs are usually free and often include expanded views of assembled parts along with helpful hints and advice. Sometimes the only place where this information is available is at trade shows associated with automotive training conferences and expos. Go to the following websites for examples of training conferences with trade shows.

Identifix

Autohotlineusa

Taylor Automotive Tech-Line

www.CARSevent.com

Aspire

www.avtechexpo.com

SEE FIGURE 15–4

www.visionkc.com (Vision Expo)

REVIEW QUESTIONS 1. What is included in the vehicle owner’s manual that could be helpful for a service technician?

3. Explain why factory service manuals or factory electronic service information are the most detailed of all service information.

5. List additional types of service manuals that are available.

CHAPTER QUIZ 1. What type of information is commonly included in the owner’s manual that would be a benefit to service technicians? a. Maintenance reminder light reset procedures b. Tire pressure monitoring system reset procedures c. Maintenance items specifications d. All of the above

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2. Two technicians are discussing the need for the history of the vehicle. Technician A says that an accident could cause faults due to hidden damage. Technician B says that some faults could be related to a previous repair. Which technician is correct? a. Technician A only c. Both Technicians A and B b. Technician B only d. Neither Technician A nor B

3. The viscosity of engine oil is found where? a. Owner’s manual b. Factory service manual or service information c. Lubrication guide d. All of the above

8. Hotline services are ______________. a. Free b. Available for a service fee c. Available on CD or DVD format d. Accessed by the Internet

9. Aftermarket parts catalogs can be a useful source of information and they are usually ______________. a. Free b. Available by paid subscription c. Available on CD or DVD d. Available for a fee on a secured Internet site

5. What type of manual includes time needed to perform service procedures? a. Flat-rate manuals c. Factory service manuals b. Owner’s manuals d. Parts guide 6. Component location can be found in ______________. a. Factory service manuals b. Owner’s manuals c. Component location manuals d. Both a and c

10. Which type of manual or service information includes the flatrate time and the cost of parts? a. Parts and time guides b. Factory service manuals c. Component location guides d. Free Internet sites

7. Aftermarket service information is available in what format? a. Manuals c. Internet b. CDs or DVDs d. All of the above

PARTS OF A VEHICLE The names of the parts of a vehicle are based on the location and purpose of the component.

LEFT SIDE OF THE VEHICLE—RIGHT SIDE OF THE VEHICLE Both of these terms refer to the left and right as if the driver is sitting behind the steering wheel. Therefore, the left side (including components under the hood) is on the driver’s side.

FRONT AND REAR The proper term for the back portion of any vehicle is rear (for example, left rear tire).

FRONT-WHEEL DRIVE VERSUS REAR-WHEEL DRIVE Front-wheel drive (FWD) means that the front wheels are being driven by the engine, as well as turned by the steering wheel. Rearwheel drive (RWD) means that the rear wheels are driven by the engine. If the engine is in the front, it can be either front- or rear-wheel drive. In many cases, a front engine vehicle can also drive all four wheels called four-wheel drive (4WD) or all-wheel drive (AWD). If the engine is located at the rear of the vehicle, it can be rear-wheel drive or four-wheel (AWD) drive.

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FIGURE 16–1 Typical vehicle identification number (VIN) as viewed through the windshield.

FIGURE 16–2 A VECI label on a 2008 Ford. A ⫽ 1980/2010

L ⫽ 1990/2020

Y ⫽ 2000/2030

B ⫽ 1981/2011

M ⫽ 1991/2021

1 ⫽ 2001/2031

N ⫽ 1992/2022

2 ⫽ 2002/2032

1 ⫽ United States

9 ⫽ Brazil

U ⫽ Romania

C ⫽ 1982/2012

2 ⫽ Canada

J ⫽ Japan

V ⫽ France

D ⫽ 1983/2013

P ⫽ 1993/2023

3 ⫽ 2003/2033

3 ⫽ Mexico

K ⫽ Korea

W ⫽ Germany

E ⫽ 1984/2014

R ⫽ 1994/2024

4 ⫽ 2004/2034

4 ⫽ United States

L ⫽ China

X ⫽ Russia

F ⫽ 1985/2015

S ⫽ 1995/2025

5 ⫽ 2005/2035

T ⫽ 1996/2026

6 ⫽ 2006/2036

5 ⫽ United States

R ⫽ Taiwan

Y ⫽ Sweden

G ⫽ 1986/2016

6 ⫽ Australia

S ⫽ England

Z ⫽ Italy

H ⫽ 1987/2017

V ⫽ 1997/2027

7 ⫽ 2007/2037

8 ⫽ Argentina

T ⫽ Czechoslovakia

J ⫽ 1988/2018

W ⫽ 1998/2028

8 ⫽ 2008/2038

K ⫽ 1989/2019

X ⫽ 1999/2029

9 ⫽ 2009/2039

CHART 16–1

CHART 16–2 VIN Year Chart (The Pattern Repeats Every 30 Years)

VEHICLE IDENTIFICATION All service work requires that the vehicle, including the engine and accessories, be properly identified. The most common identification is the make, model, and year of the vehicle. Make: e.g., Chevrolet Model: e.g., Impala Year: e.g., 2007 The year of the vehicle is often difficult to determine exactly. A model may be introduced as the next year’s model as soon as January of the previous year. Typically, a new model year (abbreviated MY) starts in September or October of the year prior to the actual new year, but not always. This is why the vehicle identification number, usually abbreviated VIN, is so important. SEE FIGURE 16–1. Since 1981, all vehicle manufacturers have used a VIN that is 17 characters long. Although every vehicle manufacturer assigns various letters or numbers within these 17 characters, there are some constants, including:

The first number or letter designates the country of origin. SEE CHART 16–1.

The model of the vehicle is commonly the fourth and/or fifth character.

The eighth character is often the engine code. (Some engines cannot be determined by the VIN number.) The tenth character represents the calendar year (abbreviated CY) on all vehicles. SEE CHART 16–2.

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VEHICLE SAFETY CERTIFICATION LABEL A vehicle safety certification label is attached to the left side pillar post on the rearward-facing section of the left front door. This label indicates the month and year of manufacture as well as the gross vehicle weight rating (GVWR), the gross axle weight rating (GAWR), and the vehicle identification number (VIN).

VECI LABEL The vehicle emissions control information (VECI) label under the hood of the vehicle shows informative settings and emission hose routing information. SEE FIGURE 16–2. The VECI label (sticker) can be located on the bottom side of the hood, the radiator fan shroud, the radiator core support, or the strut towers. The VECI label usually includes the following information.

Engine identification

Emissions standard that the vehicle meets

Vacuum hose routing diagram

Base ignition timing (if adjustable)

Spark plug type and gap

Valve lash

Emission calibration code

ZEV—Zero-Emission Vehicle. A California standard prohibiting any tailpipe emissions. The ZEV category is largely restricted to electric vehicles and hydrogen-fueled vehicles. In these cases, any emissions that are created are produced at another site, such as a power plant or hydrogen reforming center, unless such sites run on renewable energy.

NOTE: A battery-powered electric vehicle charged from the power grid will still be up to 10 times cleaner than even the cleanest gasoline vehicles over their respective lifetimes. The current California ZEV regulation allows manufacturers a choice of two options for meeting the ZEV requirements.

EMISSION STANDARDS IN THE UNITED STATES In the United States, emissions standards are managed by the Environmental Protection Agency (EPA) as well as some U.S. state governments. Some of the strictest standards in the world are formulated in California by the California Air Resources Board (CARB).

TIER 1 AND TIER 2

Federal emission standards are set by the Clean Air Act Amendments (CAAA) of 1990 grouped by tier. All vehicles sold in the United States must meet Tier 1 standards that went into effect in 1994 and are the least stringent. Additional Tier 2 standards have been optional since 2001, and were completely adopted in 2009. The current Tier 1 standards are different between automobiles and light trucks (SUVs, pickup trucks, and minivans), but Tier 2 standards are the same for both types. There are several ratings that can be given to vehicles, and a certain percentage of a manufacturer’s vehicles must meet different levels in order for the company to sell its products in affected regions. Beyond Tier 1, and in order by stringency, are the following levels.

TLEV—Transitional Low-Emission Vehicle. More stringent for HC than Tier 1.

LEV—(also known as LEV I)—Low-Emission Vehicle. An intermediate California standard about twice as stringent as Tier 1 for HC and NOX.

1. Vehicle manufacturers can meet the ZEV obligations by meeting standards that are similar to the ZEV rule as it existed in 2001. This means using a formula allowing a vehicle mix of 2% pure ZEVs, 2% AT-PZEVs (vehicles earning advanced technology partial ZEV credits), and 6% PZEVs (extremely clean conventional vehicles). The ZEV obligation is based on the number of passenger cars and small trucks a manufacturer sells in California. 2. Manufacturers may also choose a new alternative ZEV compliance strategy of meeting part of the ZEV requirement by producing the sales-weighted market share of approximately 250 fuel-cell vehicles. The remainder of the ZEV requirements could be achieved by producing 4% AT-PZEVs and 6% PZEVs. The required number of fuel-cell vehicles will increase to 2,500 from 2009 to 2011, 25,000 from 2012 through 2020, and 50,000 from 2015 through 2017. Manufacturers can substitute battery electric vehicles for up to 50% of the fuel-cell vehicle requirements. PZEV—Partial-Zero-Emission Vehicle. Compliant with the SULEV standard; additionally has near-zero evaporative emissions and a 15-year/150,000-mile warranty on its emission control equipment. Tier 2 standards are even more stringent. Tier 2 variations are appended with “II,” such as LEV II or SULEV II. Other categories have also been created.

ILEV—Inherently Low-Emission Vehicle.

AT-PZEV—Advanced Technology Partial-Zero-Emission Vehicle. If a vehicle meets the PZEV standards and is using high-technology features, such as an electric motor or highpressure gaseous fuel tanks for compressed natural gas, it qualifies as an AT-PZEV. Hybrid electric vehicles such as the Toyota Prius can qualify, as can internal combustion engine vehicles that run on natural gas (CNG), such as the Honda Civic GX. These vehicles are classified as “partial” ZEV because they receive partial credit for the number of ZEV vehicles that automakers would otherwise be required to sell in California.

NLEV—National Low-Emission Vehicle. All vehicles nationwide must meet this standard, which started in 2001. SEE CHARTS 16–3 AND 16–4.

FEDERAL EPA BIN NUMBER

The higher the tier number, the newer the regulation; the lower the bin number, the cleaner the vehicle. The 2004 Toyota Prius is a very clean Bin 3, while the Hummer H2 is a dirty Bin 11. Examples include:

Tier 1: The former federal standard; carried over to model year 2004 for those vehicles not yet subject to the phase-in.

CALIBRATION CODES Calibration codes are usually located on powertrain control modules (PCMs) or other controllers. Some calibration codes are only accessible with a scan tool. Whenever diagnosing an engine operating fault, it is often necessary to know the calibration code to be sure that the vehicle is the subject of a technical service bulletin or other service procedure. SEE FIGURE 16–4.

CASTING NUMBERS Whenever an engine part such as a block is cast, a number is put into the mold to identify the casting. SEE FIGURE 16–5. These casting numbers can be used to check dimensions such

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CHART 16–5 EPA Tier 2—120,000-Mile Tailpipe Emission Limits NOTE: The bin number is determined by the type and weight of the vehicle. The highest bin allowed for vehicles built after January 1, 2007, is Bin 8. Data compiled from the Environmental Protection Agency (EPA).

U.S. EPA VEHICLE INFORMATION PROGRAM (THE HIGHER THE SCORE, THE LOWER THE EMISSIONS) SELECTED EMISSIONS STANDARDS

as the cubic inch displacement and other information. Sometimes changes are made to the mold, yet the casting number is not changed. Most often the casting number is the best piece of identifying information that the service technician can use for identifying an engine.

FIGURE 16–5 Engine block identification number cast into the block is used for identification. FIGURE 16–4 A typical computer calibration sticker on the case of the controller. The information on the sticker is often needed when ordering parts or a replacement controller.

REVIEW QUESTIONS 1. From what position are the terms left and right determined?

3. What information is included on the VECI label under the hood?

2. What are the major pieces of information that are included in the vehicle identification number (VIN)?

4. What does Tier 2 Bin 5 mean?

CHAPTER QUIZ 1. The passenger side is called the ________. a. Right side b. Left side c. Either right or left side, depending on how the vehicle is viewed d. Both a and b

2. A vehicle with the engine in the front can be ________. a. Front-wheel drive c. Four-wheel drive b. Rear-wheel drive d. All of the above

8. What are the characters that are embedded in most engine blocks and are used for identification? a. VIN c. Bin number b. Calibration codes d. Casting number

3. The vehicle identification number (VIN) is how many characters long? a. 10 c. 17 b. 12 d. 21 4. The tenth character represents the year of the vehicle. If the tenth character is a “Y,” what year is the vehicle? a. 1998 c. 2002 b. 2000 d. 2004 5. The first character of the vehicle identification number is the country of origin. Where was the vehicle built that has a “5” as the first character? a. United States c. Mexico b. Canada d. Japan

9. If the first character of the VIN is an “S,” where was the vehicle made? a. United States c. Canada b. Mexico d. England 10. Technician A says that the lower the bin number is, the cleaner. Technician B says that SULEV has cleaner standards than ULEV. Which technician is correct? a. Technician A only b. Technician B only c. Both Technicians A and B d. Neither Technician A nor B

Preventative maintenance (PM) means periodic service work performed on a vehicle that will help keep it functioning correctly for a long time. All vehicle manufacturers publish a list of service work to be performed on a regular basis. Preventative maintenance is also called routine maintenance because it is usually performed on a set scheduled routine. The interval specified for preventative maintenance is often expressed in time and miles (km) such as:

Every six months (could be longer for many vehicles)

Every 5,000 to 10,000 miles (8,000 to 16,000 km) depending on the vehicle and how it is being operated

Either of the above, whichever occurs first

Prior to any service work, it is wise to check the vehicle for damage and document the work order if any damage is found. In most dealerships and shops, this is the responsibility of the following personnel.

Service adviser (service writer) or

Shop foreman or

Shop owner

The designated person should check the vehicle for the following: 1. Body damage 2. Missing wheel covers 3. Glass damage such as a cracked windshield 4. Any faults in the paint or trim 5. Valid license plates

PROTECT THE VEHICLE Before most service work is done, protect the inside of the vehicle by using commercially available plastic or paper protective coverings for the following areas.

Seats

Floor

Steering wheel

SEE FIGURE 17–1

6. Under-vehicle inspection and fluid checks 7. Air-conditioning system inspection and service 8. Safety inspection, such as all lights and windshield wiper blades 9. Routine cleaning of vehicle both inside and out

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PROTECT THE TECHNICIAN

Before starting routine preventative maintenance on a vehicle be sure to perform the following: 1. Open the hood (engine compartment cover). Often the struts that hold a hood open are weak or defective. Therefore, before

FIGURE 17–2 An exhaust system hose should be connected to the tailpipe(s) whenever the engine is being run indoors.

TECH TIP Do No Harm As stated in the Hippocratic oath, a doctor agrees first to do no harm to the patient during treatment. Service technicians should also try to do no harm to the vehicle while it is being serviced. Always ask, “Am I going to do any harm if I do this?” before you do it.

FIGURE 17–1 Before service begins, be sure to cover the seats, floor, and steering wheel with protective coverings. starting to work under the hood, always make sure that the hood is securely held open. 2. Connect an exhaust system hose to the tailpipe(s) before work is started that will involve operating the engine. SEE FIGURE 17–2. 3. Wear personal protective equipment (PPE) including: Safety glasses Hearing protection if around air tools or other loud noises Gloves if handling hot objects or chemicals such as used engine oil

4. On hybrid vehicles, make sure that the technician has possession of the key transmitter and that the vehicle is not in the ready mode before starting any inspection or service procedures.

SAFETY INSPECTION A safety inspection is usually recommended to be performed anytime the vehicle is in the shop for service or repair. These inspections should include all of the following: 1. Exterior lights, including: a. Headlights (high and low beam) b. Tail lights c. Turn signals d. License plate light e. Parking lights 2. Horn

WINDSHIELD WIPER AND WASHER FLUID SERVICE WINDSHIELD WIPERS Windshield wiper blades are constructed of rubber and tend to become brittle due to age. Wiper blades should be cleaned whenever the vehicle is cleaned using water and a soft cloth. Wiper blade or wiper blade insert replacement includes the following steps.

Turn the ignition switch to on (run).

Turn the wiper switch on and operate the wipers.

When the wipers are located in an easy-to-reach location, turn the ignition switch off. The wipers should stop.

Remove the insert or the entire blade as per service information and/or the instructions on the replacement windshield wiper blade package.

After double-checking that the wiper is securely attached, turn the ignition switch on (run).

Turn the wiper switch off and allow the wipers to reach the park position. Check for proper operation.

FIGURE 17–5 A cabin filter can be accessed either through the glove compartment or under the hood on most vehicles.

Most windshield washer fluid looks like blue water. It is actually water with an alcohol (methanol) additive to prevent freezing and to help clean the windshield by dissolving bugs. Be careful not to spill any washer fluid when filling the reservoir because the corrosiveness can harm wiring and electronic components. CAUTION: Some mixed fluids are for summer use only and do not contain antifreeze protection. Read the label carefully!

WARNING Windshield washer fluid usually contains methanol, a poisonous chemical that can cause blindness if ingested.

CABIN FILTER REPLACEMENT

(a)

A cabin filter is used in the heating, ventilation, and air-conditioning (HVAC) system to filter the outside air drawn into the passenger compartment. Some filters contain activated charcoal to help eliminate odors. The cabin air filter should be replaced often—every year or every 12,000 miles (19,000 km). The cabin air filter can be accessed from:

Under the hood at the cowl (bulkhead) or

Under the dash, usually behind the glove (instrument panel) compartment (Check service information for the exact location and servicing procedures for the vehicle being serviced.)

SEE FIGURE 17–5.

(b)

FIGURE 17–4 (a) The windshield wiper fluid reservoir cap is usually labeled with a symbol showing a windshield washer. (b) Use only the recommended washer fluid. Never use antifreeze in the windshield washer reservoir.

WINDSHIELD WASHER FLUID Windshield washer fluid level should be checked regularly and refilled as necessary. Use only the fluid that is recommended for use in vehicle windshield washer systems. SEE FIGURE 17–4.

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AIR FILTER INSPECTION/ REPLACEMENT An air filter filters dirt from the air before it enters the intake system of the engine. The air filter should be replaced according to vehicle manufacturer’s recommendations. Over time, the filter will start to get clogged and decrease the engine’s efficiency. Many vehicle manufacturers recommend replacing the air filter every 30,000 miles (50,000 km), or more frequently under dusty conditions. Many service

(a)

FIGURE 17–7 A master cylinder with a transparent reservoir. The brake fluid level should be between the MAX and the MIN levels as marked on the reservoir.

Metal or nontransparent plastic reservoir. This type of reservoir used on older vehicles requires that the cover be removed to check the level of the brake fluid. The proper level of brake fluid should be 0.25 inch (6 mm) from the top.

CAUTION: Do not overfill a brake master cylinder. The brake fluid gets hotter as the brakes are used and there must be room in the master cylinder reservoir for the brake fluid to expand. (b)

FIGURE 17–6 (a) A typical dirty air filter. (b) Always check the inlet passage leading to the air filter for debris that can reduce airflow to the engine.

BRAKE FLUID TYPES Brake fluid is made from a combination of various types of glycol, a non-petroleum-based fluid. Brake fluid is a polyalkylene-glycol-ether mixture, called polyglycol for short. All polyglycol brake fluid is clear to amber in color.

technicians recommend replacing the air filter every year. SEE FIGURE 17–6.

CAUTION: DOT 3 brake fluid is a very strong solvent and can remove paint! Care is required when working with this type brake fluid to avoid contact with the vehicle’s painted surfaces. It also takes the color out of leather shoes.

BRAKE FLUID INSPECTION BRAKE FLUID LEVEL Brake fluid is used to transmit the force of the driver’s foot on the brake pedal, called the service brake, to each individual wheel brake. The brake fluid should be checked at the same time the engine oil is changed, or every six months, whichever occurs first. It is normal for the brake fluid level to drop as the disc brake pads wear. Therefore, when the fluid level is low, check for two possible causes.

All automotive brake fluid must meet Federal Motor Vehicle Safety Standard 116. The Society of Automotive Engineers (SAE) and the Department of Transportation (DOT) have established brake fluid specification standards.

DOT 3. The DOT 3 brake fluid is most often used. It absorbs moisture and, according to SAE, can absorb 2% of its volume in water per year. Moisture is absorbed by the brake fluid through microscopic seams in the brake system and around seals. Over time, the water will corrode the system and thicken the brake fluid. Moisture can cause a spongy brake pedal because the increased concentration of water within the fluid boils at lower temperatures and can result in vapor lock. DOT 3 must be used from a sealed (capped) container. If allowed to remain open for any length of time, DOT 3 will absorb moisture from the surrounding air. SEE FIGURE 17–8.

DOT 4. The DOT 4 brake fluid is formulated for use by all vehicles, imported or domestic. It is commonly called low moisture absorption (LMA) because it does not absorb water as fast as DOT 3. It is still affected by moisture, however, and should be used only from a sealed container. The cost of DOT 4 is approximately double the cost of DOT 3.

DOT 5. The DOT 5 type is commonly called silicone brake fluid. It is made from polydimethylsiloxanes. Because it does

CAUSE 1 Normal disc brake pad wear (Inspect the brakes if the fluid level is low.) CAUSE 2 A leak somewhere in the hydraulic brake system (Carefully inspect the entire brake system for leaks if the brakes are not worn and the brake fluid level is low.) There are two types of brake master cylinders.

Transparent reservoir. This type allows viewing of the brake fluid (and hydraulic clutch master cylinder if so equipped) without having to remove the cover of the reservoir. The proper level should be between the MIN (minimum) level indicated and the MAX (maximum) level indicated on the clear plastic reservoir. SEE FIGURE 17–7.

What Is Used in the Clutch Master Cylinder? Vehicles equipped with a manual transmission often use a hydraulically operated clutch. This type of clutch operation uses a master cylinder and a slave cylinder near the clutch assembly. When the driver depresses the clutch pedal, the hydraulic pressure created in the master cylinder is transferred to the slave cylinder which moves and actuates the clutch. Most hydraulic clutches use DOT 3 brake fluid. Check to see that the level is between the maximum and the minimum levels as shown by lines on the reservoir. If low, check for a leak in the system as it is not normal for brake fluid level to decrease over time.

not absorb water, it is called nonhygroscopic. DOT 5 brake fluid does not mix with and should not be used with DOT 3 or DOT 4 brake fluid. NOTE: Even though DOT 5 does not normally absorb water, it is still tested using standardized SAE procedures in a humidity chamber. After a fixed amount of time, the brake fluid is measured for boiling point. Because it has had a chance to absorb moisture, the boiling point after this sequence is called the minimum wet boiling point. DOT 5 brake fluid is purple (violet), to distinguish it from DOT 3 or DOT 4 brake fluid.

DOT 5.1. The DOT 5.1 brake fluid is a non-silicone-based polyglycol fluid that is clear to amber in color. This severeduty fluid has a boiling point of over 500°F,(260°C) equal to the boiling point of silicone-based DOT 5 fluid. Unlike DOT 5, the DOT 5.1 fluid can be mixed with either DOT 3 or DOT 4 according to the brake fluid manufacturer’s recommendations.

CAUTION: Some vehicle manufacturers, such as Chrysler, do not recommend the use of or the mixing of other types of polyglycol brake fluid and specify the use of DOT 3 brake fluid only. Always follow the vehicle manufacturer’s recommendation.

BRAKE FLUID TESTING

Visual inspection. Check the color of the brake fluid. It should be clear or almost clear. If it is dark brown or black, it should be replaced.

Test strips. A quick and easy way to check the condition of the brake fluid is to use test strips. Always follow the instructions that come with the test strips for accurate results. SEE FIGURE 17–9.

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FREQUENTLY ASKED QUESTION

Boiling point. The boiling point of brake fluid can be tested using a handheld tester. Follow the instructions that come with the tester.

CAUTION: If any mineral oil such as engine oil, automatic transmission fluid (ATF), or power steering fluid gets into the brake fluid, the rubber seals will swell and cause damage to the entire braking system. Every part that includes a rubber seal will require replacement.

ENGINE OIL INSPECTION OIL LEVEL

The oil level should be checked when the vehicle is parked on level ground and after the engine has been off for at least several minutes. The oil level indicator, commonly called a dipstick, is clearly marked and in a convenient location. SEE FIGURE 17–10. To check the oil, remove the dipstick, wipe off the oil, and reinsert it all the way down. Once again remove the dipstick and check where the oil level touches the indicator. The “add” mark is usually at the 1 quart low point. SEE FIGURE 17–11.

FIGURE 17–10 A typical oil level indicator (dipstick).

EN

G

IN

Normal Use

Severe Use

Most trips over 10 miles (16 km).

Most trips less than 4 to 10 miles (6 to 16 km).

Operating a vehicle when the outside temperature is above freezing (32°F/0°C).

Operating the vehicle when the outside temperature is below freezing (32°F/0°C).

Most trips do not include slow or stop-and-go driving.

Most trips include slow or stop-and-go driving.

Not towing a trailer or carrying a heavy load.

Towing a trailer or hauling a heavy load.

Driving without dusty conditions.

Driving in dusty conditions.

No police, taxi, or commercial use of the vehicle.

Use by police, taxi, or commercial operation.

The oil change interval recommended by most vehicle manufacturers under normal conditions is 7,500 miles (12,000 km) or six months, whichever occurs first.

The oil change interval recommended by most vehicle manufacturers operating under severe conditions is every 3,000 miles (4,800 km) or every three months, whichever occurs first.

E

O

IL

CHART 17–1 MIN

MAX

The difference been “normal” and “severe” use as specified by many vehicle manufacturers.

ADD 1 QT. AT MIN.

FIGURE 17–11 The oil level should be between the MAX and the MIN marks when the vehicle is on level ground and the oil has had time to drain into the oil pan.

?

FREQUENTLY ASKED QUESTION

?

FREQUENTLY ASKED QUESTION

How Does an Oil Life Monitor Work?

Can I Switch from Synthetic Oil to Regular Oil? Yes. All oil is miscible, meaning that it can be readily mixed. Therefore, synthetic oil can be used one time and then regular mineral oil used the next time. Most important, however, is that the oil be changed at intervals that are never longer than specified by the vehicle manufacturer.

If oil needs to be added, use the specified oil and add to the engine through the oil fill opening (not through the dipstick hole as is done with automatic transmission fluid).

ENGINE OIL CHANGE INTERVALS Most automotive experts recommend that the engine oil be replaced and a new oil filter installed every 5,000 to 7,500 miles (8,000 to 12,000 km) or every six months, whichever occurs first. Most vehicles since the early 2000s have used an oil life monitor system to notify the driver when the engine oil should be changed. The oil life monitor will light a dash lamp when the oil needs to be changed. Most vehicle manufacturers recommend that the oil be changed according to a “normal” or “severe use” schedule. SEE CHART 17–1. Most vehicles are driven under severe conditions if all of the factors above are considered. Always follow the vehicle manufacturer’s recommended oil change intervals. See Chapter 22 for details on oils and oil change procedure.

While some vehicle manufacturers, such as Mercedes, use a sensor to measure oil temperature and acidity, most vehicle oil change monitors function three ways: 1. Vehicle mileage. This is the most commonly used vehicle service monitoring system. When a certain number of miles has occurred since it was reset, the control (usually the powertrain control module (PCM)) will turn on a dash light that states maintenance is required. 2. Oil life computer program. A computer program called an algorithm, or a series of mathematical calculations, is used to determine the life of the engine oil. For example, when the oil change warning light is reset, the oil life is reset to 100%. Then the PCM tracks the number of engine starts, the outside temperature, when the engine was started (based on intake air temperature [IAT] sensor input), and the number of miles traveled. Because long drives are easier on engine oil than short stop-and-go driving, the PCM deducts numbers faster during this condition. 3. Oil condition sensor. This sensor measures the dielectric properties of the oil, which changes when exposed to water, soot, ash, and glycol in the oil. A computer program takes the information from the sensor about the changes of the dielectric property of the oil to determine when to light the “change oil” lamp.

WARNING Remove the pressure cap only on a cold engine as the coolant will boil when pressure is released. This occurs because the coolant temperature is above the boiling point but it does not boil due to the pressure. When the pressure is released, all of the hot coolant immediately boils and expands outward from the opening where the cap was installed. The resulting geyser of boiling hot coolant can cause serve burns or even death.

FIGURE 17–12 Visually check the level and color of coolant in the coolant recovery or surge tank.

3. Maintenance should also include a visual inspection for signs of coolant system leaks and for the condition of the coolant hoses and accessory drive belts.

COOLANT TESTING

?

FREQUENTLY ASKED QUESTION

Visual inspection. Coolant should be clean and close to the color when it was new. If dark or muddy, it should be replaced. Milky colored coolant is an indication of oil in the system that might be caused by a defective engine gasket. If the coolant is dark or muddy looking, it should be replaced.

Test strips. Coolant test strips are available to test the condition of the coolant. Check to see that the test strips are being used on the specified type of coolant as some will work only on the old green inorganic additive technology (IAT) coolant.

Boiling/freezing points (refractometer and hydrometer). A hydrometer can be used to check the freezing and boiling temperatures of the coolant. A refractometer can be used to check the freezing temperature of the coolant.

Proper reading. A proper 50-50 mix of antifreeze and water should result in a freezing temperature of ⫺34°F (⫺37°C).

What Is the Magnuson-Moss Act? The Magnuson-Moss Act, passed into law in 1975, allows the use of non–original equipment replacement parts during the service or repair of a vehicle without losing the factory warranty. This means that any oil or air filter, spark plug, or other service part can be used unless the vehicle manufacturer furnishes these parts for free during the warranty period. The vehicle manufacturer cannot deny paying a warranty claim for a fault unless the replacement part is proved to be the cause of the condition needed to be covered by the warranty. Therefore, it is up to the business owner, service manager, or technician to determine if the replacement part is of good quality. While this is very difficult or impossible, unless defects are obviously visible, the best solution is to use the original equipment manufacturer (OEM) parts or service parts from a well-known company.

COOLING SYSTEM INSPECTION

If the freezing temperature is higher than ⫺34°F (such as ⫺20°F), there is too much water in the coolant. If the freezing temperature is lower than ⫺34°F (such as ⫺46°F), there is too much antifreeze in the coolant. SEE FIGURE 17–13.

NOTE: Many hybrid electric vehicles use two separate cooling systems—one for the internal combustion engine (ICE) and the other to cool the electronics. Check service information for the exact procedures to follow. See Chapter 20 for more details on coolant and coolant testing.

STEPS INVOLVED

Normal maintenance involves an occasional check of the following items. 1. Coolant level in the coolant recovery tank or in the surge tank SEE FIGURE 17–12. 2. The front of the radiator should be carefully inspected and cleaned of bugs, dirt, or mud that can often restrict airflow.

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ANTIFREEZE/COOLANT DISPOSAL

Used coolant drained from vehicles can usually be disposed of according to federal, state, and local laws. Check with recycling companies authorized by local or state government for the exact method recommended for disposal in your area. SEE FIGURE 17–14.

(a)

FIGURE 17–15 Using a hand-operated pressure tester. Do not exceed the pressure rating of the radiator cap when pressurizing the system. This vehicle had a leaking upper radiator that only leaked when the system was pressurized.

sucked closed, since the lower hose is attached to the suction side of the water pump. The bypass hose (if equipped) and heater hoses come in the following inside diameter sizes.

(b)

FIGURE 17–13 (a) A refractometer is used to measure the freezing point of coolant. A drop of coolant is added to a viewing screen, the lid is closed, and then held up to the light to view the display on the tool. (b) The use of tests strips is a convenient and cost-effective method to check coolant condition and freezing temperature.

1/2 inch

5/8 inch

3/4 inch

The heater hoses connect the engine cooling system to the heater core. A heater core looks like a small radiator and is located inside the vehicle. All automotive hose is constructed of rubber with reinforcing fabric weaving for strength. Sections of the coolant lines can be made from nylon-reinforced plastic or metal. All hoses should be inspected for leaks (especially near hose clamps), cracks, swollen areas indicating possible broken reinforcing material, and excessively brittle, soft, and swollen sections. Using a hand-operated pressure pump attached to the radiator opening is an excellent way to check for leaks. SEE FIGURE 17–15.

EMISSION-RELATED HOSES

Rubber hoses are also used in the following locations and for the following purposes.

FIGURE 17–14 Used coolant should be stored in a leak-proof container until it can be recycled or disposed of according to local, state, or federal laws. Note that the storage barrel is placed inside another container to catch any coolant that may spill out of the inside container.

RADIATOR AND HEATER HOSES

Upper and lower radiator hoses must be pliable, yet not soft. The lower radiator hose will be reinforced or contain an inner spring to prevent the hose from being

Positive crankcase ventilation (PCV) system hose. This type of hose has engine vacuum and requires specially designed hose if replacing the hose used for the PCV system.

Exhaust gas recirculation (EGR) system hose. This type of hose has engine vacuum and requires specially designed hose if replacing the hose used for the EGR system.

Secondary air injection (SAI) system hoses. This type of hose has engine vacuum or low pressure air and requires specially designed hose if replacing the hose used for the SAI system.

HOSE CLAMPS

There are several types of hose clamps used depending on the make, model, and year of vehicle. The three basic types are as follows: 1. Worm drive (also called a screw band type) 2. Banded-type clamp 3. Wire clamp (spring type) SEE FIGURE 17–16.

To check the automatic transmission fluid, perform the following steps.

HOSE CLAMP PLIERS

FIGURE 17–16 Hose clamps come in a variety of shapes and designs.

TECH TIP The Cut-and-Peel Trick It is often difficult to remove a radiator or heater hose from the fittings on the radiator or heater core. To avoid possible damage to expensive radiator or heater cores, do not pull or twist the hose to remove it. Simply use a utility knife and slit the hose lengthwise and then use your finger to peel the hose off of the radiator or heater core. Although this procedure will not work if the hose is to be reused, it is a real time saver when it comes to replacing old hoses. Sometimes using an angled pick that is dulled at the end will do a good job breaking the hose free.

STEP 1

Start the engine and move the gear selector to all gear positions and return to park or neutral as specified by the vehicle manufacturer.

STEP 2

Remove the transmission/transaxle dipstick (fluid level indicator) and wipe it off using a clean cloth.

STEP 3

Reinsert the dipstick until fully seated. Remove the dipstick again and note the level. SEE FIGURE 17–17.

NOTE: Some transmissions or transaxles do not use a dipstick. Check service information for the exact procedure to follow to check the fluid level. Some vehicles require the use of a scan tool to check the level of the fluid.

The automatic transmission fluid (ATF) is another important fluid that should be checked regularly. Most automatic transmission fluid levels should be checked under the following conditions.

The vehicle should be parked on a level surface.

The transmission fluid should be at normal operating temperature. This may require the vehicle to be driven several miles before the level is checked.

The engine should be running with the transmission in neutral or park as specified by the vehicle manufacturer.

NOTE: Honda and Acura manufacturers usually specify that the transmission fluid be checked with the engine off. The recommended procedure is usually stamped on the transmission dipstick or written in the owner’s manual and/or service manual.

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Do not overfill any automatic transmission/transaxle. Even if just 1/2 quart too much were added by mistake (for example, adding 1 quart when the fluid was at the “add” line instead of the correct amount of 1/2 quart) could cause the fluid to foam. Foaming of the ATF is caused by the moving parts inside the transmission/transaxle, which stir up the fluid and introduce air into it. This foamy fluid cannot adequately lubricate or operate the hydraulic clutches that make the unit function correctly.

Smell the ATF on the dipstick. If it seems burned or rancid, further service of the automatic transmission/transaxle will be necessary. Look at the color of the fluid. It should be red or light brown. A dark brown or black color indicates severe oxidation usually caused by too high an operating temperature. Further service and diagnosis of the automatic transmission/ transaxle will be required.

NOTE: Chrysler warns that color and smell should not be used to determine the condition of ATF⫹4 used in most Chrysler-built vehicles since the 2000 model year. The dyes and additives can change during normal use and it is not an indication of fluid contamination. This is true for most highly friction-modified ATF. Always follow the vehicle manufacturer’s recommendation.

TYPES OF AUTOMATIC TRANSMISSION FLUID

Automatic transmission fluid is high-quality oil that has additives that resist oxidation, inhibit rust formation, and allow the fluid to flow easily at all temperatures. The automatic transmission fluid is dyed red for identification. Various vehicle manufacturers recommend a particular type of ATF based mainly on its friction characteristics. Friction is needed between the bands, plates, and clutches of an automatic transmission/transaxle.

FIGURE 17–18 Most vehicles use a combination filler cap and level indicator (dipstick) that shows the level of power steering fluid in the reservoir.

TECH TIP

FIGURE 17–19 A special tool is useful when installing a new accessory drive belt. The long-handled wrench fits in a hole of the belt tensioner.

The Paper Towel Test New ATF will penetrate a paper towel better than used oxidized ATF. To compare old fluid with new, place three drops of new fluid on a paper towel and three drops of used ATF on the paper towel about 3 inches from the first sample. Wait for 30 minutes. The new ATF will have expanded (penetrated through the paper towel) much farther than the old, oxidized fluid. This test can be used to convince a customer that the ATF should be changed according to the vehicle manufacturer’s recommended interval even though, to the naked eye, the fluid looks okay.

The types of power steering fluid can include:

Automatic transmission fluid (check for the exact type)

Power steering fluid

Unique fluid that is specially designed for the vehicle

CAUTION: Do not use fluid that is labeled for all vehicles as this type may not be compatible with the seals used in the power steering system or provide the specified friction additives needed to provide the proper steering feel to the driver.

See Chapter 128 for additional information about automatic transmission fluid and service procedures. Always use the exact ATF recommended by the vehicle manufacturer.

ACCESSORY DRIVE BELT INSPECTION

POWER STEERING FLUID CHECKING POWER STEERING FLUID

Check power steering fluid level with the engine off. The cap for the power steering reservoir is marked with an icon of a steering wheel or the words “power steering.” Remove the cap by twisting it counterclockwise and use the level indicator as part of the cap to determine the level. Often the level marks are for cold and hot fluid.

If too low, check for leaks especially at the high-pressure lines and fittings. Add the specified fluid to the correct level. If too high, use a fluid siphon pump or a “turkey baster” and remove the excess fluid until the level is correct.

TYPES OF POWER STEERING FLUID

The correct power steering fluid is critical to the operation and service life of the power steering system! The exact power steering fluid to use varies by vehicle manufacturer and sometimes between models made by the same vehicle manufacturer because of differences among various steering component manufacturers. Always check service information for the specified fluid to use. SEE FIGURE 17–18.

TYPES OF BELTS

Older V-belts (so-named because of their shape) are 34 degrees at the V. The pulley they ride through is generally 36 degrees. This 2-degree difference results in a wedging action and makes power transmission possible, but it is also the reason why V-belts must be closely inspected. It is generally recommended that all belts, including the serpentine (or Poly V) belts be replaced every four to seven years. When a belt that turns the water pump breaks, the engine could rapidly overheat causing serious engine damage, and if one belt breaks, it often causes the other belts to become tangled, causing them to break. SEE FIGURES 17–19 AND 17–20.

BELT TENSION MEASUREMENT There are four ways that vehicle manufacturers specify that the belt tension is within factory specifications. 1. Belt tension gauge. A belt tension gauge is needed to achieve the specified belt tension. Install the belt and operate the engine with all of the accessories turned on to “run-in” the belt

for at least five minutes. Adjust the tension of the accessory drive belt to factory specifications or use the table below for an example of the proper tension based on the size of the belt. SEE FIGURE 17–21. Serpentine Belts Number of Ribs Used

Tension Range (lb)

3

45–60

4

60–80

5

75–100

6

90–125

7

105–145

V-Belts V-Belt Top Width (in.)

Tension Range (lb)

1/4

45–65

5/16

60–85

25/64

85–115

31/64

105–145

Lower-than-normal alternator output could be the result of a loose or slipping drive belt. All belts (V and serpentine multigroove) use an interference angle between the angle of the Vs of the belt and the angle of the Vs on the pulley. Over time this interference angle is worn off the edges of the V of the belt. As a result, the belt may start to slip and make a squealing sound even if tensioned properly. A fast method to determine if the noise is from the belt is to spray water from a squirt bottle at the belt with the engine running. If the noise stops, the belt is the cause of the noise. The water quickly evaporates; therefore, water simply finds the problem, it does not provide a short-term fix.

2. Marks on a tensioner. Many tensioners have marks that indicate the normal operating tension range for the accessory drive belt. Check service information for the preferred location of the tensioner mark. SEE FIGURE 17–22. 3. Torque wrench reading. Some vehicle manufacturers specify that a beam-type torque wrench be used to determine the torque needed to rotate the tensioner. If the torque reading is below specifications, the tensioner must be replaced. 4. Deflection. Depress the belt between the two pulleys that are the farthest apart and the flex or deflection should be 0.5 inch.

BELT ROUTING GUIDE

Always check the belt routing diagram located on the underhood sticker or in service information for the proper routing when replacing an accessory drive belt. The belt routing can vary depending on engine size and accessories.

TIRE AND WHEEL SERVICE INFLATION PRESSURE

Replace any serpentine belt that has more than three cracks in any one rib that appears in a 3 inch span.

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Tire pressure should be checked when the tires are cold. As a vehicle is driven, the flexing of the tire and friction between the tire and the road causes an increase in temperature.

FIGURE 17–23 The specified tire inflation pressure is printed on a placard on the driver’s door or doorpost. This information may also be located in the glove compartment, the owner’s manual, and in service information.

As the tire heats up, the air inside the tire also increases in temperature.

The increased temperature of the air increases the air pressure inside the tire.

The air pressure typically increases in pressure 4 to 6 psi after the vehicle has been driven several miles.

If air is then removed from the hot tire, the tire would be underinflated. The tire pressure specified is for a tire that has not been driven and is therefore cold, so the air pressure should be checked before the vehicle has been driven more than 2 miles (3 km).

FIGURE 17–24 An electronic tire pressure gauge is usually more accurate than a mechanical “pencil type” gauge and more likely to provide consistent pressure readings. Do not allow air to escape when testing or the reading will not be accurate. TECH TIP

NOTE: Tire pressure changes according to air temperature about 1 psi per 10°F; therefore, during a change of season the tire pressure has to be adjusted. For example, when the summer temperature of 80°F changes to 40°F in the fall, the tire pressure will drop about 4 psi (80 ⴚ 40 ⴝ 40).

Two Quick Checks If the vehicle is hoisted on a frame-contact lift, perform two quick checks: 1. Spin each tire to check that the brakes are not dragging. You should be able to turn all four wheels by hand if the parking brake is off and the transmission is in neutral. 2. When spinning the tire, look over the top of the tire to check if it is round. An improperly mounted tire or a tire that is out-of-round due to a fault in the tire can be detected by watching for the outside of the tire to move up and down as it is being rotated.

HOW TO CHECK TIRE PRESSURE Use a good-quality tire pressure gauge and push it against the tire valve stem after removing the cap. Be sure no air escapes when the pressure gauge is used as this will cause an inaccurate reading. Compare the pressure reading with the specified tire pressure. The specified pressure is located on a placard attached to the driver’s door or doorpost or in the glove compartment. SEE FIGURE 17–23. CAUTION: Do not inflate tires to the maximum rating on the tire sidewall. Even though this pressure represents the maximum tire pressure, inflating the tires to this pressure usually results in a very harsh ride and often unacceptable handling.

SPECIFIED TIRE PRESSURE

The specified tire inflation pressure should always be used when checking or adjusting tire pressure. Tire pressure should be checked and adjusted if necessary after a tire rotation has been completed because some vehicles require different inflation pressure for front and rear tires. Therefore, when the tires are rotated, the front and rear tire inflation pressure may need to be adjusted. The spare tire should also be checked at each oil change interval. Check service information for the exact inflation pressure. The recommendation sometimes includes a statement about tire pressures to use if operating under all highway-driving conditions or operating the vehicle in a fully loaded condition. Specifications for these conditions commonly include increasing the pressure, usually about 4 to 6 psi (27 to 41 kPa). SEE FIGURE 17–24.

TIRE INSPECTION

All tires should be carefully inspected for faults in the tire itself or for signs that something may be wrong with

the steering or suspension systems of the vehicle. The tires should be checked for the following conditions.

Thread depth (2/32 of an inch is the standard minimum allowable tread depth in most states)

Unequal wear

Cuts in the tread or sidewall

Bulges or uneven sidewalls

Check the spare tire for proper inflation pressure as well as condition of the tire and wheel. See Chapter 114 for additional information on tire service procedure.

TIRE ROTATION

To assure long life and even tire wear, it is important to rotate each tire to another location. Some rear-wheeldrive vehicles, for example, may show premature tire wear on the front tires. The wear usually starts on the outer tread row and usually appears as a front-to-back (high and low) wear pattern on individual tread blocks. These blocks of tread rubber are deformed during cornering, stopping, and turning, which can cause tire noise and/or tire roughness. While some shoulder wear on front tires is normal, it can be reduced by proper inflation, alignment, and tire rotation. SEE FIGURE 17–25 for suggested methods of rotation.

FIGURE 17–26 (a) A torque absorbing adaptor commonly called a “torque stick” is being used to tighten lug nuts. The adapter should not be held during the tightening process because this can affect the torque applied and could cause personal injury if the torque stick broke. (b) A color-coded assortment of torque sticks. FULL "X"

FRONT/REAR

(ACCEPTABLE)

(ACCEPTABLE)

FIGURE 17–25 The method most often recommended is the modified X method. Using this method, each tire eventually is used at each of the four wheel locations. An easy way to remember the sequence, whether front-wheel drive or rear-wheel drive, is “Drive wheels straight, cross the nondrive wheels.” NOTE: Radial tires can cause a radial pull due to their construction. If the wheel alignment is correct, attempt to correct a pull by rotating the tires front to rear or, if necessary, side to side. HINT: To help remember when to rotate the tires, just remember that it should be done at every other oil change. Most manufacturers recommend changing the engine oil every 5,000 miles (8,000 km) or every six months and recommend tire rotation every 10,000 (16,000 km) miles or every year.

WHEEL MOUNTING TORQUE There are two commonly used methods to ensure proper tire lug nut torque.

Torque wrench. Using a torque wrench is the preferred method to tighten the wheel lug nuts.

Torque sticks. These long sticks are calibrated to transmit a limited amount of torque to the lug nut when used according to factory instructions. Make certain that the wheel studs are

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TECH TIP Check for Wheel Lock Key Many vehicles have wheel locks that require a special key to remove. The wise technician should always ask the customer or service writer about wheel locks before pulling the vehicle into the shop or before the vehicle is hoisted.

clean and dry and torqued to manufacturer’s specifications. Most vehicles specify a tightening torque of between 80 and 100 lb-ft (108 and 136 N-m). CAUTION: Most manufacturers warn that the wheel studs should not be oiled or lubricated with grease because this can cause the wheel lug nuts to loosen while driving. Always tighten lug nuts gradually, in the proper sequence (tighten one nut, skip one, and tighten the next nut), to prevent warping the brake drums or rotors, or bending a wheel. SEE FIGURE 17–26. NOTE: Anytime you install a brand-new set of aluminum wheels, retorque the wheels after the first 25 miles. The soft aluminum often compresses slightly, loosening the torque on the wheels.

FIGURE 17–27 A hand-operated grease gun is being used to lubricate the steering component through a grease fitting.

FIGURE 17–28 Most vehicle manufacturers recommend the use of grease meeting the NLGI #2 and “GC” for wheel bearings and “LB” for chassis lubrication. Many greases have both designations and therefore can be used for wheel bearings or chassis lubrication.

REAL WORLD FIX

TECH TIP

Waiting for the Second Click Story A student service technician was observed applying a lot of force to a clicker-type torque wrench attached to a wheel lug nut. When the instructor asked what he was doing, the student replied that he was turning the lug nut tighter until he heard a second click from the torque wrench. This was confusing to the instructor until the student explained that he had heard a second click of the torque wrench during the demonstration. The instructor at once realized that the student had heard a click when the proper torque was achieved, plus another click when the force on the torque wrench was released. No harm occurred to the vehicle because all of the lug nuts were reinstalled and properly torqued. The instructor learned that a more complete explanation for the use of click-type torque wrenches was needed.

Watch Out for Vents that Look Like Grease Fittings Watch for what looks like a grease (Zerk) fitting but is somewhat smaller, as this may be a vent such as found on a late-model Dodge Caravan on the ball joints. If the grease gun does not fit on it, do not be tempted to remove and replace with a grease fitting. STEP 4

If the fitting will not accept grease, replace it with a new one and retry.

STEP 5

Remove the grease gun and wipe any spilled grease from the fitting.

CAUTION: If too much grease is forced into a sealed grease boot, the boot itself may rupture, requiring the entire joint to be replaced.

TYPES OF GREASE Vehicle manufacturers specify the type and consistency of grease for each application. The technician should know what these specifications mean. Grease is oil with a thickening agent added to allow it to be installed in places where a liquid lubricant would not stay. Greases are named for their thickening agent, such as aluminum, barium, calcium, lithium, or sodium.

CHASSIS LUBRICATION GREASE FITTINGS

Chassis lubrication refers to the greasing of parts that rub against each other or installing grease into a pivot (or ball joints) through a grease fitting. Grease fittings are also called Zerk fittings (named for Oscar U. Zerk) or Alemite fittings (named for the manufacturer of early grease fittings). These fittings contain a one-way check valve that prevents the grease from escaping. Grease fittings are used on steering components, such as tie-rod ends, and in the suspension ball joints, which require lubrication to prevent wear and noise caused by the action of a ball rotating within a joint during vehicle operation. SEE FIGURE 17–27. The procedure for greasing a grease fitting includes the following steps. STEP 1

Wipe off the fitting with a shop cloth.

STEP 2

Make sure the grease gun coupler is fully seated on the fitting.

STEP 3

Apply grease only until the dust boot swells.

CAUTION: Grease types are often not compatible with each other. The American Society for Testing Materials (ASTM) specifies the consistency of grease using a penetration test. The National Lubricating Grease Institute (NLGI) uses the penetration test as a guide to assign the grease a number. Low numbers are very fluid and higher numbers are more firm or hard. Most vehicle manufacturers specify NLGI #2 for wheel bearing and chassis lubrication. SEE FIGURE 17–28. NLGI also specifies grease by its use, as follows:

The “GC” designation is acceptable for wheel bearings.

The “LB” designation is acceptable for chassis lubrication.

Many greases are labeled with both GC and LB and are therefore acceptable for both wheel bearings and chassis use, such as in lubricating ball joints and tie-rod ends.

FIGURE 17–29 This differential assembly has been leaking fluid. The root cause should be determined and the unit filled to the proper level using the specified lubricant, to help prevent early failure and an expensive repair later.

FIGURE 17–30 Always ensure that the fill plug can be accessed and removed before draining the fluid from a manual transmission.

TECH TIP Check the Fill Plug Before Draining a Transmission Experienced technicians have learned that it is wise to check that the fill plug can be removed before draining the manual transmission or transfer case through the drain plug. If the fill plug cannot be removed, then the fluid should not be drained until the problem is resolved. Once the fluid has been drained, there is no option but to do whatever it takes to get the fill plug open. This process is often difficult and may result in having to replace the entire assembly. SEE FIGURE 17–30.

DIFFERENTIAL FLUID CHECK PROCEDURE FOR CHECKING

Rear-wheel-drive vehicles use a differential in the rear of the vehicle to change the direction of power flow from the engine to the rear wheels. The differential also provides a gear reduction to increase engine torque applied to the drive wheels. Four-wheel-drive vehicles also use a differential at the front of the vehicle in addition to the differential in the rear. To check the differential fluid level and condition, perform the following steps.

STEP 1

Hoist the vehicle safely.

STEP 2

Visually check for any signs of leakage. SEE FIGURE 17–29.

STEP 3

Remove the inspection plug from the side or rear cover of the differential assembly.

STEP 4

Insert your small finger into the hole in the housing and then remove your finger. If the differential fluid is on your finger, then the fluid level is okay. Rub the fluid between your fingers. If the fluid is not gritty feeling, reinstall the inspection plug. If the fluid is gritty feeling, further service will be necessary to determine the cause and correct it. If the differential fluid is not on your finger, then the fluid level is too low.

NOTE: The reason for the low fluid level should be determined. If repairs are not completed immediately, additional differential fluid should be added by pumping it into the differential through the inspection hole.

DIFFERENTIAL LUBRICANTS

All differentials use hypoid gear sets; and a special lubricant is necessary because the gears both roll and slide between their meshed teeth. Gear lubes are specified by the American Petroleum Institute (API). Most differentials require: 1. SAE 80W-90 GL-5 or

Locate the transmission/transaxle inspection (fill) plug. Consult the factory service manual for the proper plug to remove, to check the fluid level.

If the fluid drips out of the hole, then the level is correct. If the fluid runs out of the hole, the level is too full. Allow it to flow out until it stops. The correct level of fluid is at the bottom of the inspection hole.

If low, first determine the correct fluid to use and then fill until the fluid level is at the bottom of the inspection hole or until the fluid runs out of the inspection hole.

FIGURE 17–31 A broken coil spring was found during an undervehicle inspection. The owner was not aware of a problem and it did not make any noise, but the vehicle stability was affected.

UNDER-VEHICLE INSPECTION

FIGURE 17–32 This corroded muffler was found during a visual inspection, but was not detected by the driver because it was relatively quiet.

Brake lines for evidence of damage or leakage

Shock absorbers for leakage or damaged mounts

Steering linkage for obvious looseness or damaged or missing parts

Parking brake cable guides

VISUAL CHECKS

Other items underneath the vehicle that may need checking or lubricating include:

Shock absorbers and springs. SEE FIGURE 17–31.

Transmission/transaxle shift linkage (check the service manual for the correct lubricant to use)

Exhaust system including all pipes and hangers. SEE FIGURE 17–32.

CAUTION: Do not lubricate plastic-coated parking brake cables. The lubricant can destroy the plastic coating.

REVIEW QUESTIONS 1. Why should brake fluid not be filled above the full or MAX level as indicated on the master cylinder reservoir? 2. Why should brake fluid be kept in an airtight container?

3. How do you check differential fluid? 4. What are four lubricants that a manual transmission/transaxle may require depending on exact year, make, and model of the vehicle.

CHAPTER QUIZ 1. When should the engine oil be replaced? a. According to the vehicle manufacturer’s recommended interval based on time and mileage, whichever occurs first b. Every three months regardless of miles c. Every 3,000 miles regardless of time d. All of the above

5. Coolant can be checked using ______________. a. Boiling/freezing points using a refractometer and hydrometer b. Visual inspection c. Test strips d. All of the above

6. Accessory drive belt tension is determined by ______________. a. Marks on the tensioner b. Torque required to rotate the tensioner using a beam-type torque wrench c. Belt tension using a belt tension gauge d. Any of the above depending on the specified procedure as found in service information.

3. The cabin filter can be accessed from ______________. a. Under the hood on some vehicles b. Under the dash on some vehicles c. From under the vehicle on some vehicles d. Either a or b 4. Before draining a manual transmission to replace the fluid, what should the technician do first? a. Check service information for the specified fluid b. Check to see if the fill plug can be removed c. Purchase SAE 80W-90 gear lube d. Both a and b

7. Using the modified X tire rotation method on a front-wheel-drive vehicle would place the right front tire on the ______________. a. Left front c. Right rear b. Left rear d. Right front 8. Most vehicle manufacturers specify a lug nut (wheel nut) tightening torque specification of about ______________. a. 80 to 100 lb-ft c. 125 to 150 lb-ft b. 100 to 125 lb-ft d. 150 to 175 lb-ft

10. A service technician removed the inspection/fill plug from the differential of a rear-wheel- drive vehicle and gear lube started to flow out. Technician A says to quickly replace the plug to prevent any more loss of gear lube. Technician B says to catch the fluid and allow the fluid to continue to drain. Which technician is correct? a. Technician A only c. Both Technicians A and B b. Technician B only d. Neither Technician A nor B

PURPOSE AND FUNCTION The purpose and function of an engine is to convert the heat energy of burning fuel into mechanical energy. In a typical vehicle, mechanical energy is then used to perform the following:

Propel the vehicle

Power the air-conditioning system and power steering

Produce electrical power for use throughout the vehicle

ENERGY AND POWER Engines use energy to produce power. The chemical energy in fuel is converted to heat energy by the burning of the fuel at a controlled rate. This process is called combustion. If engine combustion occurs within the power chamber, the engine is called an internal combustion engine.

FIGURE 18–1 The rotating assembly for a V-8 engine that has eight pistons and connecting rods and one crankshaft.

NOTE: An external combustion engine burns fuel outside of the engine itself, such as a steam engine. Engines used in automobiles are internal combustion heat engines. They convert the chemical energy of the gasoline into heat within a power chamber that is called a combustion chamber. Heat energy released in the combustion chamber raises the temperature of the combustion gases within the chamber. The increase in gas temperature causes the pressure of the gases to increase. The pressure developed within the combustion chamber is applied to the head of a piston to produce a usable mechanical force, which is then converted into useful mechanical power.

FIGURE 18–2 A cylinder head with four valves per cylinder, two intake valves (larger) and two exhaust valves (smaller).

?

ENGINE CONSTRUCTION OVERVIEW

FREQUENTLY ASKED QUESTION

What Is a Flat-Head Engine?

BLOCK All automotive and truck engines are constructed using a solid frame, called a block. A block is constructed of cast iron or aluminum and provides the foundation for most of the engine components and systems. The block is cast and then machined to very close tolerances to allow other parts to be installed. ROTATING ASSEMBLY Pistons are installed in the block and move up and down during engine operation. Pistons are connected to connecting rods, which connect the pistons to the crankshaft. The crankshaft converts the up-and-down motion of the piston to rotary motion, which is then transmitted to the drive wheels and propels the vehicle. SEE FIGURE 18–1.

A flat-head engine is an older type engine design that has the valves in the block. The valves are located next to the cylinders and the air-fuel mixture, and exhaust flows through the block to the intake and exhaust manifolds. Because the valves are in the block, the heads are flat and, therefore, are called flat-head engines. The most commonly known was the Ford flat-head V-8 produced from 1932 until 1953. Typical flat-head engines included: • • • • •

All engines use a cylinder head to seal the top of the cylinders, which are in the engine block. The cylinder head also contains both intake valves that allow air and fuel into the cylinder and exhaust valves, which allow the hot gases left over to escape from the engine. Cylinder heads are constructed of cast iron or aluminum and are then machined for the valves and other valverelated components. SEE FIGURE 18–2.

INTAKE AND EXHAUST MANIFOLDS Air and fuel enter the engine through an intake manifold and exit the engine through the exhaust manifold. Intake manifolds operate cooler than exhaust manifolds and are therefore constructed of nylon-reinforced plastic or aluminum. Exhaust manifolds must be able to withstand hot exhaust gases, so most are constructed from cast iron or steel tubing.

COOLING SYSTEM All engines must have a cooling system to control engine temperatures. While some older engines were air cooled, all current production passenger vehicle engines are cooled by circulating antifreeze coolant through passages in the block and cylinder head. The coolant picks up the heat from the engine and after the thermostat opens, the water pump circulates the coolant through the radiator where the excess heat is released to the outside air, cooling the coolant. The coolant is continuously circulated through the cooling system and the temperature is controlled by the thermostat. SEE FIGURE 18–3.

LUBRICATION SYSTEM

All engines contain moving and sliding parts that must be kept lubricated to reduce wear and friction. The oil pan, bolted to the bottom of the engine block, holds 4 to 7 quarts (4 to 7 liters) of oil. An oil pump, which is driven by the engine, forces the oil through the oil filter and then into passages in the crankshaft and block. These passages are called oil galleries. The oil is also forced up to the valves and then falls down through openings in the cylinder head and block, then back into the oil pan. SEE FIGURE 18–4.

FUEL SYSTEM AND IGNITION SYSTEM

All engines require both a fuel system to supply fuel to the cylinders and an ignition system to ignite the air-fuel mixture in the cylinders. The fuel system includes the following components.

FIGURE 18–3 The coolant temperature is controlled by the thermostat, which opens and allows coolant to flow to the radiator when the temperature reaches the rating temperature of the thermostat.

Fuel tank, where fuel is stored and where most fuel pumps are located

Fuel filter and lines, which transfer the fuel for the fuel tank to the engine

Fuel injectors, which spray fuel into the intake manifold or directly into the cylinder, depending on the type of system used

The ignition system is designed to take 12 volts from the battery and convert it to 5,000 to 40,000 volts needed to jump the gap of a spark plug. Spark plugs are threaded into the cylinder head of each cylinder, and when the spark occurs, it ignites the air-fuel mixture in the cylinder creating pressure and forcing the piston down in the cylinder. The following components are part of the ignition system.

This sequence repeats as the engine rotates. To stop the engine, the electricity to the ignition system is shut off by the ignition switch, which stops the spark to the spark plugs. The combustion pressure developed in the combustion chamber at the correct time will push the piston downward to rotate the crankshaft.

THE 720-DEGREE CYCLE Each cycle (four strokes) of events requires that the engine crankshaft make two complete revolutions, or 720 degrees (360 degrees ⫻ 2 ⫽ 720 degrees). Each stroke of the cycle requires that the crankshaft rotate 180 degrees. The greater the number of cylinders, the closer together the power strokes of the individual cylinders will occur. The number of degrees that the crankshaft rotates between power strokes can be expressed as an angle. To find the angle between cylinders of an engine, divide the number of cylinders into 720 degrees. Angle with 3 cylinders: 720/3 ⫽ 240 degrees Angle with 4 cylinders: 720/4 ⫽ 180 degrees Angle with 5 cylinders: 720/5 ⫽ 144 degrees

PRINCIPLES

The first four-stroke cycle engine was developed by a German engineer, Nickolaus Otto, in 1876. Most automotive engines use the four-stroke cycle of events. The process begins by the starter motor rotating the engine until combustion takes place. The four-stroke cycle is repeated for each cylinder of the engine. SEE FIGURE 18–5. A piston that moves up and down, or reciprocates, in a cylinder can be seen in Figure 18–5. The piston is attached to a crankshaft with a connecting rod. This arrangement allows the piston to reciprocate (move up and down) in the cylinder as the crankshaft rotates. SEE FIGURE 18–6.

OPERATION

Engine cycles are identified by the number of piston strokes required to complete the cycle. A piston stroke is a one-way piston movement either from top to bottom or bottom to top of the cylinder. During one stroke, the crankshaft rotates 180 degrees (1/2 revolution). A cycle is a complete series of events that continually repeats. Most automobile engines use a four-stroke cycle.

Intake stroke. The intake valve is open and the piston inside the cylinder travels downward, drawing a mixture of air and fuel into the cylinder. The crankshaft rotates 180 degrees from top dead center (TDC) to bottom dead center (BDC) and the camshaft rotates 90 degrees.

Compression stroke. As the engine continues to rotate, the intake valve closes and the piston moves upward in the cylinder, compressing the air-fuel mixture. The crankshaft rotates 180 degrees from bottom dead center (BDC) to top dead center (TDC) and the camshaft rotates 90 degrees.

Power stroke. When the piston gets near the top of the cylinder, the spark at the spark plug ignites the air-fuel mixture, which forces the piston downward. The crankshaft rotates 180 degrees from top dead center (TDC) to bottom dead center (BDC) and the camshaft rotates 90 degrees.

Exhaust stroke. The engine continues to rotate, and the piston again moves upward in the cylinder. The exhaust valve opens, and the piston forces the residual burned gases out of the exhaust valve and into the exhaust manifold and exhaust system. The crankshaft rotates 180 degrees from bottom dead center (BDC) to top dead center (TDC) and the camshaft rotates 90 degrees.

Angle with 6 cylinders: 720/6 ⫽ 120 degrees Angle with 8 cylinders: 720/8 ⫽ 90 degrees Angle with 10 cylinders: 720/10 ⫽ 72 degrees This means that in a 4-cylinder engine, a power stroke occurs at every 180 degrees of the crankshaft rotation (every 1/2 rotation). A V-8 is a much smoother operating engine because a power stroke occurs twice as often (every 90 degrees of crankshaft rotation).

ENGINE CLASSIFICATION AND CONSTRUCTION Engines are classified by several characteristics, including:

Number of strokes. Most automotive engines use the fourstroke cycle.

Cylinder arrangement. An engine with more cylinders is smoother operating because the power pulses produced by the power strokes are more closely spaced. An inline engine places all cylinders in a straight line. The 4-, 5-, and 6-cylinder engines are commonly manufactured inline engines. A V-type engine, such as a V-6 or V-8, has the number of cylinders split and built into a V shape. SEE FIGURE 18–7. Horizontally opposed 4- and 6-cylinder engines have two banks of cylinders that are horizontal, resulting in a low engine. This style of engine is used in Porsche and Subaru engines, and is often called the boxer or pancake engine design. SEE FIGURE 18–8.

Longitudinal and transverse mounting. Engines may be mounted either parallel with the length of the vehicle (longitudinally) or crosswise (transversely). SEE FIGURES 18–9 AND 18–10. The same engine may be mounted in various vehicles in either direction. NOTE: Although it might be possible to mount an engine in different vehicles both longitudinally and transversely, the engine component parts may not be interchangeable. Differences can include different engine blocks and crankshafts, as well as different water pumps.

Valve and camshaft number and location. The number of valves per cylinder and the number and location of camshafts

FIGURE 18–5 The downward movement of the piston draws the air-fuel mixture into the cylinder through the intake valve on the intake stroke. On the compression stroke, the mixture is compressed by the upward movement of the piston with both valves closed. Ignition occurs at the beginning of the power stroke, and combustion drives the piston downward to produce power. On the exhaust stroke, the upward-moving piston forces the burned gases out the open exhaust valve.

are major factors in engine operation. A typical older-model engine uses one intake valve and one exhaust valve per cylinder. Many newer engines use two intake and two exhaust valves per cylinder. The valves are opened by a camshaft. Some engines use one camshaft for the intake valves and a separate camshaft for the exhaust valves. When the camshaft is located in the block, the valves are operated by lifters, pushrods, and rocker arms.

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This type of engine is called:

A pushrod engine

Cam-in-block design

Overhead valve (OHV), because an overhead valve engine has the valves located in the cylinder head ( SEE FIGURE 18–11.)

When one overhead camshaft is used, the design is called a single overhead camshaft (SOHC) design. When two overhead

ENGINE

DIFFERENTIAL

PROPELLER SHAFT OR DRIVESHAFT

REAR AXLES UNIVERSAL JOINTS

TRANSMISSION CLUTCH OR TORQUE CONVERTER

FIGURE 18–9 A longitudinally mounted engine drives the rear wheels through a transmission, driveshaft, and differential assembly. TRANSMISSION AND DIFFERENTIAL

camshafts are used, the design is called a double overhead camshaft (DOHC) design. SEE FIGURES 18–12 AND 18–13.

V-8 ENGINE

FIGURE 18–7 Automotive engine cylinder arrangements.

NOTE: A V-type engine uses two banks or rows of cylinders. An SOHC design, therefore, uses two camshafts but only one camshaft per bank (row) of cylinders. A DOHC V-6, therefore, has four camshafts, two for each bank.

Type of fuel. Most engines operate on gasoline, whereas some engines are designed to operate on ethanol (E85), methanol (M85), natural gas, propane, or diesel fuel.

Cooling method. Most engines are liquid cooled, but some older models were air cooled. Air-cooled engines, such as the original VW Beatle, could not meet exhaust emission standards.

Type of induction pressure. If atmospheric air pressure is used to force the air-fuel mixture into the cylinders, the engine is called naturally aspirated. Some engines use a turbocharger or supercharger to force the air-fuel mixture into the cylinder for even greater power.

A successful alternative engine design is the rotary engine, also called the Wankel engine after its inventor, Felix Heinrich Wankel (1902–1988), a German inventor. The Mazda RX-7 and RX-8 represent the only long-term use of the rotary engine. The rotating combustion chamber engine runs very smoothly, and it produces high power for its size and weight. The basic rotating combustion chamber engine has a triangular-shaped rotor turning in a housing. The housing is in the shape of a geometric figure called a two-lobed epitrochoid. A seal on each corner, or apex, of the rotor is in constant contact with the housing, so the rotor must turn with an eccentric motion. This means that the center of the rotor moves around the center of the engine. The eccentric motion can be seen in FIGURE 18–14.

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FREQUENTLY ASKED QUESTION

Where Does an Engine Stop? LIFTER

DOUBLE OVERHEAD CAMSHAFT

FIGURE 18–12 SOHC engines usually require additional components, such as a rocker arm, to operate all of the valves. DOHC engines often operate the valves directly.

When the ignition system is turned off, the firing of the spark plugs stops and the engine will rotate until it stops due to the inertia of the rotating parts. The greatest resistance that occurs in the engine happens during the compression stroke. It has been determined that an engine usually stops when one of the cylinders is about 70 degrees before top dead center (BTDC) on the compression stroke with a variation of plus or minus 10 degrees. This explains why technicians discover that the starter ring gear is worn at two locations on a 4-cylinder engine. The engine stops at one of the two possible places depending on which cylinder is on the compression stroke.

ENGINE ROTATION DIRECTION The SAE standard for automotive engine rotation is counterclockwise (CCW) as viewed from the flywheel end (clockwise as viewed from the front of the engine). The flywheel end of the engine is the end to which the power is applied to drive the vehicle. This is called the principal end of the engine. The nonprincipal end of the engine is opposite the principal end and is generally referred to as the front of the engine, where the accessory belts are used. SEE FIGURE 18–15. Therefore, in most rear-wheel-drive vehicles, the engine is mounted longitudinally with the principal end at the rear of the engine. Most transversely mounted engines also adhere to the same standard for direction of rotation. Many Honda engines, and some marine applications, may differ from this standard.

ENGINE MEASUREMENT BORE FIGURE 18–13 A DOHC engine uses a camshaft for the intake valves and a separate camshaft for the exhaust valves in each cylinder head.

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The diameter of a cylinder is called the bore. The larger the bore, the greater the area on which the gases have to work. Pressure is measured in units, such as pounds per square inch (PSI). The greater the area (in square inches), the higher the force exerted by the pistons to rotate the crankshaft. SEE FIGURE 18–16.

ECCENTRIC GEAR ON SHAFT

COMPRESSION

INTAKE

INTAKE PORT

EXHAUST PORT

ROTOR

INTAKE

COMPRESSION

SPARK PLUGS

MAXIMUM COMPRESSION AND FIRING

POWER

EXHAUST

FIGURE 18–14 A rotary engine operates on the four-stroke cycle but uses a rotor instead of a piston and crankshaft to achieve intake, compression, power, and exhaust stroke.

FIGURE 18–16 The bore and stroke of pistons are used to calculate an engine’s displacement.

153

TECH TIP How Fast Can an Engine Rotate? Most passenger vehicle engines are designed to rotate at low speed for the following reasons. • Maximum efficiency is achieved at low engine speed. A diesel engine used in a large ship, for example, will rotate at about 100 RPM for maximum efficiency. • Piston ring friction is the highest point of friction in the engine. The slower the engine speed, the less loss to friction from the piston rings.

CENTER LINE ROD BEARING JOURNAL CENTER LINE MAIN BEARING JOURNAL

However, horsepower is what is needed to get a vehicle down the road quickly. Horsepower is torque times engine speed divided by 5,252. Therefore, a high engine speed usually indicates a high horsepower. For example, a Formula 1 race car is limited to 2.4 liter V-8 but uses a 1.6 in. (40 mm) stroke. This extremely short stroke means that the engine can easily achieve the upper limit allowed by the rules of 18,000 RPM while producing over 700 horsepower. The larger the engine, the more power the engine is capable of producing. Several sayings are often quoted about engine size:

FIGURE 18–17 The distance between the centerline of the main bearing journal and the centerline of the connecting rod journal determines the stroke of the engine. This photo is a little unusual because it shows a V-6 with a splayed crankshaft used to even out the impulses on a 90-degree, V-6 engine design.

STROKE The stroke of an engine is the distance the piston travels from top dead center (TDC) to bottom dead center (BDC). This distance is determined by the throw of the crankshaft. The throw is the distance from the centerline of the crankshaft to the centerline of the crankshaft rod journal. The throw is one-half of the stroke. SEE FIGURE 18–17. The longer this distance is, the greater the amount of air-fuel mixture that can be drawn into the cylinder. The more air-fuel mixture inside the cylinder, the more force will result when the mixture is ignited.

“There is no substitute for cubic inches.” “There is no replacement for displacement.” Although a large engine generally uses more fuel, making an engine larger is often the easiest way to increase power.

NOTE: Changing the connecting rod length does not change the stroke of an engine. Changing the connecting rod only changes the position of the piston in the cylinder. Only the crankshaft determines the stroke of an engine.

The formula is: Cubic inch displacement ⴝ ␲ (pi) ⴛ R2 ⴛ Stroke ⴛ Number of cylinders R ⫽ Radius of the cylinder or one-half of the bore. The πR2 part is the formula for the area of a circle.

DISPLACEMENT

Engine size is described as displacement. Displacement is the cubic inch (cu. in.) or cubic centimeter (cc) volume displaced or how much air is moved by all of the pistons. A liter (L) is equal to 1,000 cubic centimeters; therefore, most engines today are identified by their displacement in liters.

ENGINE SIZE CONVERSION Many vehicle manufacturers will round the displacement so the calculated cubic inch displacement may not agree with the published displacement value. SEE CHART 18–2.

V-8 ENGINE STROKE

3.50

3.75

3.875

4.00

4.125

BORE

Cu. In.

Cu. In.

Cu. In.

Cu. In.

Cu. In.

3.00

199

212

219

226

233

3.125

214

229

237

244

252

3.250

232

249

257

265

274

3.375

251

269

277

286

295

3.500

269

288

298

308

317

3.625

288

309

319

330

339

3.750

309

332

343

354

365

3.875

331

354

366

378

390

4.00

352

377

389

402

414

4.125

373

399

413

426

439

STROKE

3.50

3.75

3.875

4.00

4.125

BORE

Cu. In.

Cu. In.

Cu. In.

Cu. In.

Cu. In.

3.00

148

159

164

169

175

3.125

161

172

178

184

190

3.250

174

186

193

199

205

3.375

188

201

208

215

222

3.500

202

216

223

228

238

3.625

216

232

239

247

255

3.750

232

249

257

265

273

3.875

248

266

275

283

292

4.00

264

283

292

301

311

4.125

280

299

309

319

329

STROKE

3.50

3.75

3.875

4.00

4.125

BORE

Cu. In.

Cu. In.

Cu. In.

Cu. In.

Cu. In.

6-CYLINDER ENGINE

4-CYLINDER ENGINE

3.00

99

106

110

113

117

3.125

107

115

119

123

126

3.250

116

124

129

133

137

3.375

125

134

139

143

148

3.500

135

144

149

152

159

3.625

144

158

160

165

170

3.750

155

166

171

177

182

3.875

165

177

183

189

195

4.00

176

188

195

201

207

4.125

186

200

206

213

220

CHART 18–1 To find the cubic inch displacement, find the bore that is closest to the actual value, then go across to the closest stroke value.

COMPRESSION RATIO DEFINITION

Compression ratio (CR) is the ratio of the difference in the cylinder volume when the piston is at the bottom of the stroke to the volume in the cylinder above the piston when the piston is at the top of the stroke. The compression ratio of an engine is an important consideration when rebuilding or repairing an engine. SEE FIGURE 18–18.

CHART 18–2 Liters to cubic inches is often not exact and can result in representing several different engine sizes based on their advertised size in liters.

CLEARANCE VOLUME

COMPRESSION RATIO = 8:1

COMBUSTION CHAMBER VOLUME DECK HEIGHT

CYLINDER VOLUME

1 2 3 4 5 6 7 8

PISTON TOP AT TDC

STROKE

PISTON DISPLACEMENT

COMPRESSED HEAD GASKET 0.020 INCH

PISTON TOP AT BDC

BOTTOM DEAD CENTER

TOP DEAD CENTER

FIGURE 18–18 Compression ratio is the ratio of the total cylinder volume (when the piston is at the bottom of its stroke) to the clearance volume (when the piston is at the top of its stroke).

CALCULATING COMPRESSION RATIO

The compression

ratio (CR) calculation uses the formula: CR 5

Volume in cylinder with piston at bottom of cylinder Volume in cylinder with piston at top center

SEE FIGURE 18–19.

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CHAPTER 18

FIGURE 18–19 Combustion chamber volume is the volume above the piston when the piston is at top dead center.

For example: What is the compression ratio of an engine with 50.3 cu. in. displacement in one cylinder and a combustion chamber volume of 6.7 cu. in.? CR 5

50.3 1 6.7cu. in. 57.0 5 5 8.5 6.7 cu. in. 6.7

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1 FOOT

FREQUENTLY ASKED QUESTION

Is Torque ft-lb or lb-ft? The definition of torque is a force (lb) applied to an object times the distance from that object (ft). Therefore, based on the definition of the term, torque should be:

10 POUNDS

lb-ft (a force times a distance) Newton-meter (N-m) (a force times a distance) FIGURE 18–20 Torque is a twisting force equal to the distance from the pivot point times the force applied expressed in units called pound-feet (lb-ft) or newton-meters (N-m).

CHANGING COMPRESSION RATIO

Any time an engine is modified, the compression ratio should be checked to make sure it is either the same as it was originally or has been changed to match the diesel compression ratio. Factors that can affect compression ratio include:

Head gasket thickness. A thicker than stock gasket will decrease the compression ratio and a thinner than stock gasket will increase the compression ratio.

Increasing the cylinder size. If the bore or stroke is increased, a greater amount of air will be compressed into the combustion chamber, which will increase the compression ratio.

TORQUE AND HORSEPOWER DEFINITION OF TORQUE

Torque is the term used to describe a rotating force that may or may not result in motion. Torque is measured as the amount of force multiplied by the length of the lever through which it acts. If you use a 1 ft long wrench to apply 10 pounds (lb) of force to the end of the wrench to turn a bolt, then you are exerting 10 pound-feet (lb-ft) of torque. SEE FIGURE 18–20. Torque is the twisting force measured at the end of the crankshaft and measured on a dynamometer. Engine torque is always expressed at a specific engine speed (RPM) or range of engine speeds where the torque is at the maximum. For example, an engine may be listed as producing 275 lb-ft @ 2,400 RPM. The metric unit for torque is newton-meters, because the newton is the metric unit for force and the distance is expressed in meters. 1 pound-foot ⫽ 1.3558 newton-meters 1 newton-meter ⫽ 0.7376 pound-foot

DEFINITION OF POWER

The term power means the rate of doing work. Power equals work divided by time. Work is achieved when a certain amount of mass (weight) is moved a certain distance by a force. If the object is moved in 10 seconds

However, torque is commonly labeled, even on some torque wrenches as ft-lb.

TECH TIP Quick-and-Easy Engine Efficiency Check A good, efficient engine is able to produce a lot of power from little displacement. A common rule of thumb is that an engine is efficient if it can produce 1 horsepower per cubic inch of displacement. Many engines today are capable of this feat, such as the following: Ford: 4.6 liter V-8 (281 cu. in.): 305 hp Chevrolet: 3.0 liter V-6 (207 cu. in.): 210 hp Chrysler: 3.5 liter V-6 (214 cu. in.): 214 hp Acura: 3.2 liter V-6 (195 cu. in.): 260 hp An engine is very powerful for its size if it can produce 100 hp per liter. This efficiency goal is harder to accomplish. Most factory stock engines that can achieve this feat are supercharged or turbocharged.

or 10 minutes does not make a difference in the amount of work accomplished, but it does affect the amount of power needed. Power is expressed in units of foot-pounds per minute and power also includes the engine speed (RPM) where the maximum power is achieved. For example, an engine may be listed as producing 280 hp @ 4400 RPM.

HORSEPOWER AND ALTITUDE

Because the density of the air is lower at high altitude, the power that a normal engine can develop is greatly reduced at high altitude. According to SAE conversion factors, a nonsupercharged or nonturbocharged engine loses about 3% of its power for every 1,000 ft (300 m) of altitude. Therefore, an engine that develops 200 brake horsepower at sea level will only produce about 116 brake horsepower at the top of Pike’s Peak in Colorado at 14,110 ft (4,300 m) (3% ⫻ 14 – 42%). Supercharged and turbocharged engines are not as greatly affected by altitude as normally aspirated engines, which are those engines that breathe air at normal atmospheric pressure.

REVIEW QUESTIONS 1. What are the strokes of a four stroke cycle?

2. If an engine at sea level produces 100 hp, how many horsepower would it develop at 6,000 ft of altitude?

CHAPTER QUIZ 1. All overhead valve engines ______________. a. Use an overhead camshaft b. Have the valves located in the cylinder head c. Operate by the two-stroke cycle d. Use the camshaft to close the valves 2. An SOHC V-8 engine has how many camshafts? a. One c. Three b. Two d. Four 3. The coolant flow through the radiator is controlled by the ______________. a. Size of the passages in the block b. Thermostat c. Cooling fan(s) d. Water pump 4. Torque is expressed in units of ______________. a. Pound-feet b. Foot-pounds c. Foot-pounds per minute d. Pound-feet per second 5. Horsepower is expressed in units of ______________. a. Pound-feet c. Foot-pounds per minute b. Foot-pounds d. Pound-feet per second

7. One cylinder of an automotive four-stroke cycle engine completes a cycle every ______________. a. 90 degrees c. 360 degrees b. 180 degrees d. 720 degrees 8. How many rotations of the crankshaft are required to complete each stroke of a four-stroke cycle engine? a. One-fourth c. One b. One-half d. Two 9. A rotating force is called ______________. a. Horsepower c. Combustion pressure b. Torque d. Eccentric movement 10. Technician A says that a crankshaft determines the stroke of an engine. Technician B says that the length of the connecting rod determines the stroke of an engine. Which technician is correct? a. Technician A only c. Both Technicians A and B b. Technician B only d. Neither Technician A nor B

DIESEL ENGINES FUNDAMENTALS In 1892, a German engineer named Rudolf Diesel perfected the compression ignition engine that bears his name. The diesel engine uses heat created by compression to ignite the fuel, so it requires no spark ignition system. The diesel engine requires compression ratios of 16:1 and higher. Incoming air is compressed until its temperature reaches

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about 1,000°F (540°C). This is called heat of compression. As the piston reaches the top of its compression stroke, fuel is injected into the cylinder, where it is ignited by the hot air. SEE FIGURE 19–1. As the fuel burns, it expands and produces power. Because of the very high compression and torque output of a diesel engine, it is made heavier and stronger than the same size gasoline-powered engine. A diesel engine uses a fuel system with a precision injection pump and individual fuel injectors. The pump delivers fuel to the injectors at a high pressure and at timed intervals. Each injector sprays

INJECTOR EXHAUST VALVE

AIR INTAKE VALVE

FIGURE 19–1 Diesel combustion occurs when fuel is injected into the hot, highly compressed air in the cylinder.

INJECTOR LINE

RETURN LINE INJECTOR

SYSTEM OR COMPONENT

FUEL INJECTION PUMP

FUEL TANK

INLET LINE

FIGURE 19–3 A Cummins diesel engine as found in a Dodge pickup truck. A high-pressure pump (up to 30,000 PSI) is used to supply diesel fuel to this common rail, which has tubes running to each injector. Note the thick cylinder walls and heavy-duty construction.

Comparison between a typical gasoline and a diesel engine. fuel into the combustion chamber at the precise moment required for efficient combustion. SEE FIGURE 19–2.

ADVANTAGES AND DISADVANTAGES

A diesel engine has several advantages compared to a similar size gasoline-powered engine, including: 1. More torque output 2. Greater fuel economy 3. Long service life A diesel engine has several disadvantages compared to a similar size gasoline-powered engine, including: 1. Engine noise, especially when cold and/or at idle speed 2. Exhaust smell 3. Cold weather startability 4. Vacuum pump that is needed to supply the vacuum needs of the heat, ventilation, and air-conditioning system 5. Heavier than a gasoline engine

6. Fuel availability 7. Extra cost compared to a gasoline engine

CONSTRUCTION Diesel engines must be constructed heavier than gasoline engines because of the tremendous pressures that are created in the cylinders during operation. SEE CHART 19–1. The torque output of a diesel engine is often double or more than the same size gasoline-powered engines. AIR-FUEL RATIOS

In a diesel engine, air is not controlled by a throttle as in a gasoline engine. Instead, the amount of fuel injected is varied to control power and speed. The air-fuel mixture of a diesel can vary from as lean as 85:1 at idle to as rich as 20:1 at full load. This higher air-fuel ratio and the increased compression pressures make the diesel more fuel efficient than a gasoline engine, in part because diesel engines do not suffer from throttling losses. Throttling losses involve the power needed in a gasoline engine to draw air past a closed or partially closed throttle.

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FUEL INJECTOR INTAKE VALVE

CYLINDER HEAD

PISTON

FIGURE 19–4 A rod/piston assembly from a 5.9 liter Cummins diesel engine used in a Dodge pickup truck.

In a gasoline engine, the speed and power are controlled by the throttle valve, which controls the amount of air entering the engine. Adding more fuel to the cylinders of a gasoline engine without adding more air (oxygen) will not increase the speed or power of the engine. In a diesel engine, speed and power are not controlled by the amount of air entering the cylinders because the engine air intake is always wide open. Therefore, the engine always has enough oxygen to burn the fuel in the cylinder and will increase speed (and power) when additional fuel is supplied.

FIGURE 19–6 A direct injection diesel engine injects the fuel directly into the combustion chamber. Many designs do not use a glow plug.

All indirect diesel injection engines require the use of a glow plug which is an electrical heater that helps start the combustion process. In a direct injection (abbreviated DI) diesel engine, fuel is injected directly into the cylinder. The piston incorporates a depression where initial combustion takes place. Direct injection diesel engines are generally more efficient than indirect injection engines, but have a tendency to produce greater amounts of noise. SEE FIGURE 19–6. While some direct injection diesel engines use glow plugs to help cold starting and to reduce emissions, many direct injection diesel engines do not use glow plugs.

DIESEL FUEL IGNITION

Ignition occurs in a diesel engine by injecting fuel into the air charge, which has been heated by compression to a temperature greater than the ignition point of the fuel or about 1,000°F (538°C). The chemical reaction of burning the fuel creates heat, which causes the gases to expand, forcing the piston to rotate the crankshaft. A four-stroke diesel engine requires two rotations of the crankshaft to complete one cycle.

On the intake stroke, the piston passes TDC, the intake valve(s) opens, and filtered air enters the cylinder, while the exhaust valve(s) remains open for a few degrees to allow all of the exhaust gases to escape from the previous combustion event.

On the compression stroke, after the piston passes BDC, the intake valve(s) closes and the piston travels up to TDC (completion of the first crankshaft rotation).

On the power stroke, the piston nears TDC on the compression stroke and diesel fuel is injected into the cylinder by the injectors. The ignition of the fuel does not start immediately but the heat of compression starts the combustion phases in the cylinder. During this power stroke, the piston passes TDC and the expanding gases force the piston down, rotating the crankshaft.

On the exhaust stroke, as the piston passes BDC, the exhaust valve(s) opens and the exhaust gases start to flow out of the cylinder. This continues as the piston travels up to TDC, pumping the spent gases out of the cylinder. At TDC, the second crankshaft rotation is complete.

NOTE: Many newer diesel engines are equipped with a throttle valve. This valve is used by the emission control system and is not designed to control the speed of the engine.

INDIRECT AND DIRECT INJECTION

In an indirect injection (abbreviated IDI) diesel engine, fuel is injected into a small prechamber, which is connected to the cylinder by a narrow opening. The initial combustion takes place in this prechamber. This has the effect of slowing the rate of combustion, which tends to reduce noise. SEE FIGURE 19–5.

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THREE PHASES OF COMBUSTION There are three distinct phases or parts to the combustion in a diesel engine. 1. Ignition delay. Near the end of the compression stroke, fuel injection begins, but ignition does not begin immediately. This period is called ignition delay. 2. Rapid combustion. This phase of combustion occurs when the fuel first starts to burn, creating a sudden rise in cylinder pressure. It is this sudden and rapid rise in combustion chamber pressure that causes the characteristic diesel engine knock. 3. Controlled combustion. After the rapid combustion occurs, the rest of the fuel in the combustion chamber begins to burn and injection continues. This process occurs in an area near the injector that contains fuel surrounded by air. This fuel burns as it mixes with the air.

FIGURE 19–7 A fuel temperature sensor is being tested using an ice bath.

FUEL TANK AND LIFT PUMP PARTS INVOLVED

A fuel tank used on a vehicle equipped with a diesel engine differs from the one used with a gasoline engine in the following ways.

The filler neck is larger for diesel fuel. The nozzle size is 15/16 in. (24 mm) instead of 13/16 in. (21 mm) for gasoline filler necks. Truck stop diesel nozzles for large over-the-road trucks are usually larger, 1.25 in. or 1.5 in. (32 mm or 38 mm) to allow for faster fueling of large-capacity fuel tanks. There are no evaporative emission control devices or a charcoal (carbon) canister. Diesel fuel is not as volatile as gasoline and, therefore, diesel vehicles do not have evaporative emission control devices.

The diesel fuel is usually drawn from the fuel tank by a separate pump, called a lift pump and delivers the fuel to the injection pump. Between the fuel tank and the lift pump is a water-fuel separator. Water is heavier than diesel fuel and sinks to the bottom of the separator. Part of normal routine maintenance on a vehicle equipped with a diesel engine is to drain the water from the water-fuel separator. A float is often used inside the separator, which is connected to a warning light on the dash that lights if the water reaches a level where it needs to be drained. The water separator is often part of the fuel filter assembly. Both the fuel filter and the water separator are common maintenance items.

A diesel engine injection pump is used to increase the pressure of the diesel fuel from very low values from the lift pump to the extremely high pressures needed for injection.

NOTE: Water can cause corrosive damage and wear to diesel engine parts because it is not a good lubricant. Water cannot be atomized by a diesel fuel injector nozzle and will often “blow out” the nozzle tip. Many diesel engines also use a fuel temperature sensor. The computer uses this information to adjust fuel delivery based on the density of the fuel. SEE FIGURE 19–7.

The lift pump is a low-pressure, high-volume pump. The high-pressure injection pump is a high-pressure, low-volume pump.

Injection pumps are usually driven by a gear off the camshaft at the front of the engine. As the injection pump shaft rotates, the diesel fuel is fed from a fill port to a high-pressure chamber. If a distributortype injection pump is used, the fuel is forced out of the injection port to the correct injector nozzle through the high-pressure line. SEE FIGURE 19–8.

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FUEL INJECTION PUMP INJECTION TIMING STEPPER MOTOR

RETURN LINE

EACH OF THE HIGH PRESSURE LINES MUST BE OF EQUAL LENGTH

PIVOT ADVANCE PISTON

FUEL FILTER

ADVANCE

RETARD

LIFT PUMP

FUEL LEVEL SENSOR

INJECTOR

FUEL TANK

FIGURE 19–9 A schematic of Standadyne diesel fuel–injection pump assembly showing all of the related components.

NOTE: Because of the very tight tolerances in a diesel engine, the smallest amount of dirt can cause excessive damage to the engine and to the fuel-injection system.

DISTRIBUTOR INJECTION PUMP

A distributor diesel injection pump is a high-pressure pump assembly with lines leading to each individual injector. The high-pressure lines between the distributor and the injectors must be the exact same length to ensure proper injection timing. The high-pressure fuel causes the injectors to open. Due to the internal friction of the lines, there is a slight delay before fuel pressure opens the injector nozzle. The injection pump itself creates the injection advance needed for engine speeds above idle often by using a stepper motor attached to the advance piston, and the fuel is then discharged into the lines. SEE FIGURE 19–9. NOTE: The lines expand some during an injection event. This is how timing checks are performed. The pulsing of the injector line is picked up by a probe used to detect the injection event similar to a timing light used to detect a spark on a gasoline engine.

HIGH-PRESSURE COMMON RAIL Newer diesel engines use a fuel delivery system referred to as a high-pressure common rail (HPCR) design. Diesel fuel under high pressure, over 20,000 PSI

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(138,000 kPa), is applied to the injectors, which are opened by a solenoid controlled by the computer. Because the injectors are computer controlled, the combustion process can be precisely controlled to provide maximum engine efficiency with the lowest possible noise and exhaust emissions. SEE FIGURE 19–10.

HEUI SYSTEM PRINCIPLES OF OPERATION

Ford 7.3 and 6.0 liter (and Navistar) diesels use a system called a hydraulic electronic unit injection system, or HEUI system. The components used include:

High-pressure engine oil pump and reservoir

Pressure regulator for the engine oil

Passages in the cylinder head for flow of fuel to the injectors

OPERATION The engine oil is pressurized to provide an opening pressure strong enough to overcome the fuel pressure when the solenoid is commanded to open by the PCM. The system functions as follows:

Fuel is drawn from the tank by the tandem fuel pump, which circulates fuel at low pressure through the fuel filter/water

Ford 7.3 and 6.0 liter diesel engines pump unfiltered oil from the sump to the high-pressure oil pump and then to the injectors. This means that not changing oil regularly can contribute to accumulation of dirt in the engine and will subject the fuel injectors to wear and potential damage as particles suspended in the oil get forced into the injectors.

separator/fuel heater bowl and then fuel is directed back to the fuel pump where fuel is pumped at high pressure into the cylinder head fuel galleries.

The injectors, which are hydraulically actuated by engine oil pressure from the high-pressure oil pump, are then fired by the powertrain control module (PCM). The control system for the fuel injectors is the PCM, and the injectors are fired based on sensor inputs received by the PCM. SEE FIGURE 19–11.

HEUI injectors rely on O-rings to keep fuel and oil from mixing or escaping, causing performance problems or engine damage. HEUI injectors use five O-rings. The three external O-rings should be replaced with updated O-rings if they fail. The two internal O-rings are not replaceable and if these fail, the injector(s) must be replaced. The most common symptoms of injector O-ring trouble include:

Oil getting in the fuel

The fuel filter element turning black

FIGURE 19–11 A HEUI injector from a Ford PowerStroke diesel engine. The O-ring grooves indicate the location of the O-rings that seal the fuel section of the injector from coolant and from the engine oil.

Long cranking times before starting

Sluggish performance

Reduction in power

Increased oil consumption (This often accompanies O-ring problems or any fault that lets fuel in the oil.)

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TECH TIP Never Allow a Diesel Engine to Run Out of Fuel If a gasoline-powered vehicle runs out of gasoline, it is an inconvenience and a possible additional expense to get some gasoline. However, if a vehicle equipped with a diesel engine runs out of fuel, it can be a major concern. Besides adding diesel fuel to the tank, the other problem is getting all of the air out of the pump, lines, and injectors so the engine will operate correctly. The procedure usually involves cranking the engine long enough to get liquid diesel fuel back into the system, but at the same time keeping cranking time short enough to avoid overheating the starter. Consult service information for the exact service procedure if the diesel engine is run out of fuel. NOTE: Some diesel engines, such as the General Motors Duramax V-8, are equipped with a priming pump located under the hood on top of the fuel filter. Pushing down and releasing the priming pump with a vent valve open will purge any trapped air from the system. Always follow the vehicle manufacturer’s instructions.

Heat shield. This is the outer shell of the injector nozzle and may have external threads where it seals in the cylinder head.

Injector body. This is the inner part of the nozzle and contains the injector needle valve and spring, and threads into the outer heat shield.

Diesel injector needle valve. This precision machined valve and the tip of the needle seal against the injector body when it is closed. When the valve is open, diesel fuel is sprayed into the combustion chamber. This passage is controlled by a computer-controlled solenoid on diesel engines equipped with computer-controlled injection. Injector pressure chamber. The pressure chamber is a machined cavity in the injector body around the tip of the injector needle. Injection pump pressure forces fuel into this chamber, forcing the needle valve open.

BALL DRAIN ORIFICE HIGH-PRESSURE CONNECTION

PARTS INVOLVED Diesel injector nozzles are spring-loaded closed valves that spray fuel directly into the combustion chamber or precombustion chamber when the injector is opened. Injector nozzles are threaded or clamped into the cylinder head, one for each cylinder, and are replaceable as an assembly. The tip of the injector nozzle has many holes to deliver an atomized spray of diesel fuel into the cylinder. Parts of a diesel injector nozzle include:

RETURN SPRING

SERVO-PISTON NOZZLE SPRING PRESSURE PIN

NOZZLE NEEDLE

INJECTION NOZZLE

FIGURE 19–13 A Duramax injector showing all the internal parts.

needle valve return spring and forcing the needle valve open. When the needle valve opens, diesel fuel is discharged into the combustion chamber in a hollow cone spray pattern. Any fuel that leaks past the needle valve returns to the fuel tank through a return passage and line. SEE FIGURE 19–13.

GLOW PLUGS

DIESEL INJECTOR NOZZLE OPERATION

The electric solenoid attached to the injector nozzle is computer controlled and opens to allow fuel to flow into the injector pressure chamber. SEE FIGURE 19–12. The fuel flows down through a fuel passage in the injector body and into the pressure chamber. The high fuel pressure in the pressure chamber forces the needle valve upward, compressing the

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PURPOSE AND FUNCTION

Glow plugs are always used in diesel engines equipped with a precombustion chamber and may be used in direct injection diesel engines to aid starting. A glow plug is a heating element that uses 12 volts from the battery and aids in the starting of a cold engine by providing heat to help the fuel to ignite. SEE FIGURE 19–14.

As the temperature of the glow plug increases, the resistance of the heating element inside increases, thereby reducing the current in amperes needed by the glow plugs.

OPERATION Most glow plugs used in newer vehicles are controlled by the powertrain control module, which monitors coolant temperature and intake air temperature. The glow plugs are turned on or pulsed on or off depending on the temperature of the engine. The PCM will also keep the glow plug turned on after the engine starts, to reduce white exhaust smoke (unburned fuel) and to improve idle quality after starting. SEE FIGURE 19–15. The “wait to start” lamp (if equipped) will light when the engine and the outside temperatures are low to allow time for the glow plugs to get hot. HEATED INLET AIR Some diesel engines, such as the Dodge Cummins and the General Motors 6.6 liter Duramax V-8, use an electrical heater wire to warm the intake air to help in cold weather starting and running. SEE FIGURE 19–16.

FIGURE 19–14 A glow plug assortment showing the various types and sizes of glow plugs used. Always use the specified glow plugs.

GLOW PLUG RELAY CONTROL

ENGINE CONTROL MODULE (ECM)

HOT AT ALL TIMES

BATTERY FUSE 175 A

3

HOT IN RUN AND START

FUSE HOLDER

POWER DISTRIBUTION

FUEL HEATER FUSE 15 A

FUSIBLE LINK

FUSE BLOCK– UNDERHOOD

FUSIBLE LINK

3

GLOW PLUG RELAY

GLOW PLUG/INTAKE HEATER RELAY ASSEMBLY

INTAKE AIR (IA) HEATER RELAY FUSIBLE LINK

FUSIBLE LINK

INTAKE AIR (IA) HEATER

GLOW PLUG 2

GLOW PLUG 4

GLOW PLUG 6

GLOW PLUG 8

GLOW PLUG 1

GLOW PLUG 3

GLOW PLUG 5

GLOW PLUG 7

G101

52

C1

GLOW PLUG SIGNAL

78

29

IA HEATER RELAY CONTROL

C1

INTAKE HEATER DIAG 1

62

C2

INTAKE HEATER DIAG 2

ENGINE CONTROL MODULE

FIGURE 19–15 A schematic of a typical glow plug circuit. Notice that the glow plug relay and intake air heater relay are both computer controlled.

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APP SENSOR 5V AP

P#

4V

2

3V

APP #

3

2V 1V

AP

P#

1

0 25%

50%

75%

100%

PERCENTAGE THROTTLE OPENING

FIGURE 19–16 A wire-wound electric heater is used to warm the intake air on some diesel engines.

?

FREQUENTLY ASKED QUESTION

How Can You Tell If Gasoline Has Been Added to the Diesel Fuel by Mistake? If gasoline has been accidentally added to diesel fuel and is burned in a diesel engine, the result can be very damaging to the engine. The gasoline can ignite faster than diesel fuel, which would tend to increase the temperature of combustion. This high temperature can harm injectors and glow plugs, as well as pistons, head gaskets, and other major diesel engine components. If contaminated fuel is suspected, first smell the fuel at the filler neck. If the fuel smells like gasoline, then the tank should be drained and refilled with diesel fuel. If the smell test does not indicate a gasoline or any rancid smell, then test a sample for proper specific gravity. NOTE: Diesel fuel designed for on-road use should be green. Red diesel fuel (high sulfur) should only be found in off-road or farm equipment.

ENGINE-DRIVEN VACUUM PUMP Because a diesel engine is unthrottled, it creates very little vacuum in the intake manifold. Several engine and vehicle components operate using vacuum, such as the exhaust gas recirculation (EGR) valve and the heating and ventilation blend and air doors. Most diesels used in cars and light trucks are equipped with an engine-driven vacuum pump to supply the vacuum for these components.

FIGURE 19–17 A typical accelerator pedal position (APP) sensor uses three different sensors in one package with each creating a different voltage as the accelerator is moved.

ACCELERATOR PEDAL POSITION SENSOR Some light-truck diesel engines are equipped with an electronic throttle to control the amount of fuel injected into the engine. Because a diesel engine does not use a throttle in the air intake, the only way to control engine speed is by controlling the amount of fuel being injected into the cylinders. Instead of a mechanical link from the accelerator pedal to the diesel injection pump, a throttle-by-wire system uses an accelerator pedal position (APP) sensor. To ensure safety, it consists of three separate sensors that change in voltage as the accelerator pedal is depressed. SEE FIGURE 19–17. The computer checks for errors by comparing the voltage output of each of the three sensors inside the APP and compares them to what they should be if there are no faults. If an error is detected, the engine and vehicle speed are often reduced.

DIESEL ENGINE TURBOCHARGERS TURBOCHARGED DIESELS A turbocharger greatly increases engine power by pumping additional compressed air into the combustion chambers. This allows a greater quantity of fuel to be burned in the cylinders resulting in greater power output. In a turbocharger, the turbine wheel spins as exhaust gas flows out of the engine and drives the turbine blades. The turbine spins the compressor wheel at the opposite end of the turbine shaft, pumping air into the intake system. SEE FIGURE 19–18. AIR CHARGE COOLER

DIESEL FUEL HEATERS Diesel fuel heaters help prevent power loss and stalling in cold weather. The heater is placed in the fuel line between the tank and the primary filter. Some coolant heaters are thermostatically controlled, which allows fuel to bypass the heater once it has reached operating temperature.

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The first component in a typical turbocharger system is an air filter through which ambient air passes before entering the compressor. The air is compressed, which raises its density (mass/unit volume). All currently produced light-duty diesels use an air charge cooler whose purpose is to cool the compressed air to further raise the air density. Cooler air entering the engine means more power can be produced by the engine. SEE FIGURE 19–19.

VARIABLE TURBOCHARGER

A variable turbocharger is used on many diesel engines for boost control. Boost pressure is controlled independent of engine speed and a wastegate is not needed. The adjustable vanes mount to a unison ring that allows the vanes to move. As the position of the unison ring rotates, the vanes change angle. The vanes are opened to minimize flow at the turbine and exhaust back pressure at low engine speeds. To increase turbine speed, the vanes are closed. The velocity of the exhaust gases increases, as does the speed of the turbine. The unison ring is connected to a cam that is positioned by a rack-and-pinion gear. The turbocharger’s vane position actuator solenoid connects to a hydraulic piston, which moves the rack to rotate the pinion gear and cam. SEE FIGURE 19–20. The turbocharger vane position control solenoid valve is used to advance the unison ring’s relationship to the turbine and thereby articulate the vanes. This solenoid actuates a spool valve that applies oil pressure to either side of a piston. Oil flow has three modes: apply, hold, and release.

The turbocharger vane position actuation is controlled by the ECM, which can change turbine boost efficiency independent of engine speed. The ECM provides a control signal to the valve solenoid along with a low-side reference. A pulse-width-modulated signal from the ECM moves the valve to the desired position.

EXHAUST GAS RECIRCULATION The EGR system recycles some exhaust gas back into the intake stream to cool combustion, which reduces oxides of nitrogen (NOx) emissions. The EGR system includes:

Plumbing that carries some exhaust gas from the turbocharger exhaust inlet to the intake ports

FIGURE 19–18 A Cummins diesel turbocharger is used to increase the power and torque of the engine.

ADJUSTABLE VANES

FIGURE 19–20 A variable vane turbocharger allows the boost to be controlled without the need of a wastegate. CHARGE AIR COOLER

AMBIENT AIR INTAKE EXHAUST STROKE

COMPRESSOR

TURBINE

EXHAUST

FIGURE 19–19 An air charge cooler is used to cool the compressed air.

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FINE BEACH SAND (90μm IN. DIAMETER)

HUMAN HAIR ( -70 μm IN. DIAMETER)

FIGURE 19–21 A cutaway showing the exhaust cooler. The cooler the exhaust is, the more effective it is in controlling NOx emissions.

PM10 (< 10 μm IN. DIAMETER)

PM2.5 (< 2.5 μm IN. DIAMETER)

FIGURE 19–22 Relative size of particulate matter to a human hair.

?

The EGR valve is PCM controlled and often uses a DC stepper motor and worm gear to move the valve stem open. The gear is not attached to the valve and can only force it open. Return spring force closes the valve. The EGR valve and sensor assembly is a five-wire design. The PCM uses the position sensor to verify that valve action is as commanded.

What Is the Big Deal for the Need to Control Very Small Soot Particles? For many years soot or particulate matter (PM) was thought to be less of a health concern than exhaust emissions from gasoline engines. It was felt that the soot could simply fall to the ground without causing any noticeable harm to people or the environment. However, it was discovered that the small soot particulates when breathed in are not expelled from the lungs like larger particles but instead get trapped in the deep areas of the lungs where they accumulate.

DIESEL PARTICULATE MATTER PARTICULATE MATTER STANDARDS Particulate matter (PM), also called soot, refers to tiny particles of solid or semisolid material suspended in the atmosphere. This includes particles between 0.1 micron and 50 microns in diameter. The heavier particles, larger than 50 microns, typically tend to settle out quickly due to gravity. Particulates are generally categorized as follows:

Total suspended particulate (TSP). Refers to all particles between 0.1 and 50 microns. Up until 1987, the Environmental Protection Agency (EPA) standard for particulates was based on levels of TSP.

PM10. Refers to particulate matter of 10 microns or less (approximately 1/6 the diameter of a human hair). EPA has a standard for particles based on levels of PM10.

PM2.5. Refers to particulate matter of 2.5 microns or less (approximately 1/20 the diameter of a human hair), also called “fine” particles. In July 1997, the EPA approved a standard for PM2.5. SEE FIGURE 19–22.

SOOT CATEGORIES

In general, soot particles produced by diesel combustion fall into the following categories.

DIESEL OXIDATION CATALYST PURPOSE AND FUNCTION Diesel oxidation catalysts (DOC) are used in all light-duty diesel engines, since 2007. They consist of a flow-through honeycomb-style substrate structure that is wash coated with a layer of catalyst materials, similar to those used in a gasoline engine catalytic converter. These materials include the precious metals platinum and palladium, as well as other base metal catalysts. Catalysts chemically react with exhaust gas to convert harmful nitrogen oxide into nitrogen dioxide, and to oxidize absorbed hydrocarbons. The chemical reaction acts as a combustor for the unburned fuel that is characteristic of diesel compression ignition. The main function of the DOC is to start a regeneration event by converting the fuel-rich exhaust gases to heat. The DOC also reduces:

Carbon monoxide (CO) Hydrocarbons (HC)

Fine. Less than 2.5 microns

Ultrafine. Less than 0.1 micron, and make up 80% to 95% of soot

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FREQUENTLY ASKED QUESTION

Odor-causing compounds such as aldehydes and sulfur

SEE FIGURE 19–23.

PM H2O

NO2 CO2

SOOT BUILDUP HC PM

CO

FIGURE 19–23 Chemical reaction within the DOC.

FIGURE 19–25 The soot is trapped in the passages of the DPF. The exhaust has to flow through the sides of the trap and exit.

EGT SENSOR 1

DOC

EGT SENSOR 2

DPF

FIGURE 19–24 Aftertreatment of diesel exhaust is handled by the DOC and DPF.

DIESEL EXHAUST PARTICULATE FILTER PURPOSE AND FUNCTION Diesel exhaust particulate filters (DPFs) are used in all light-duty diesel vehicles, since 2007, to meet the exhaust emissions standards. The heated exhaust gas from the DOC flows into the DPF, which captures diesel exhaust gas particulates (soot) to prevent them from being released into the atmosphere. This is done by forcing the exhaust through a porous cell which has a silicon carbide substrate with honeycomb-cell-type channels that trap the soot. The main difference between the DPF and a typical catalyst filter is that the entrance to every other cell channel in the DPF substrate is blocked at one end. So instead of flowing directly through the channels, the exhaust gas is forced through the porous walls of the blocked channels and exits through the adjacent open-ended channels. This type of filter is also referred to as a “wall-flow” filter. SEE FIGURE 19–24. OPERATION

Soot particulates in the gas remain trapped on the DPF channel walls where, over time, the trapped particulate matter will begin to clog the filter. The filter must therefore be purged periodically to remove accumulated soot particles. The process of purging soot from the DPF is described as regeneration. When the temperature of the exhaust gas is increased, the heat incinerates the soot particles trapped in the filter and is effectively renewed. SEE FIGURE 19–25.

EXHAUST GAS TEMPERATURE SENSORS

The following two exhaust gas temperature sensors are used to help the PCM control the DPF.

FIGURE 19–26 EGT 1 and EGT 2 are used by the PCM to help control after treatment.

EGT sensor 1 is positioned between the DOC and the DPF where it can measure the temperature of the exhaust gas entering the DPF.

EGT sensor 2 measures the temperature of the exhaust gas stream immediately after it exits the DPF.

The powertrain control module monitors the signals from the EGT sensors as part of its calibrations to control DPF regeneration. Proper exhaust gas temperatures at the inlet of the DPF are crucial for proper operation and for starting the regeneration process. Too high a temperature at the DPF will cause the DPF substrate to melt or crack. Regeneration will be terminated at temperatures above 1,470°F (800°C). With too low a temperature, self-regeneration will not fully complete the soot-burning process. SEE FIGURE 19–26.

The exact location of the DPS varies by vehicle model type such as medium duty, pickup, or van. By measuring the exhaust supply (upstream) pressure from the DOC, and the post DPF (downstream) pressure, the PCM can determine differential pressure, also called “delta” pressure, across the DPF. Data from the DPF differential pressure sensor is used by the PCM to calibrate for controlling DPF exhaust system operation.

DIESEL PARTICULATE FILTER REGENERATION The primary reason for soot removal is to prevent the buildup of exhaust back pressure. Excessive back pressure increases fuel consumption, reduces power output, and can potentially cause engine

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MAIN CLEANED AREA

R E G E N E R A T I O N

PILOT

PRE

AFTER

SOOT

CLEANED AREA

FIGURE 19–27 Regeneration burns the soot and renews the DPF. damage. Several factors can trigger the diesel PCM to perform regeneration, including:

Will the Postinjection Pulses Reduce Fuel Economy? Maybe. Due to the added fuel-injection pulses and late fuel-injection timing, an increase in fuel consumption may be noticed on the driver information center (DIC) during the regeneration time period. A drop in overall fuel economy should not be noticeable. SEE FIGURE 19–28.

DPF REGENERATION PROCESS

A number of engine components are required to function together for the regeneration process to be performed, as follows: 1. PCM controls that impact DPF regeneration include late post injections, engine speed, and adjusting fuel pressure. 2. Adding late post injection pulses provides the engine with additional fuel to be oxidized in the DOC, which increases exhaust temperatures entering the DPF to 900°F (500°C) or higher. SEE FIGURE 19–27. 3. The intake air valve acts as a restrictor that reduces air entry to the engine, which increases engine operating temperature.

?

FREQUENTLY ASKED QUESTION

What Is an Exhaust Air Cooler? An exhaust air cooler is simply a section of tailpipe that has slits for air to enter. As hot exhaust rushes past the gap, outside air is drawn into the area which reduces the exhaust discharge temperature. The cooler significantly lowers exhaust temperature at the tailpipe from about 800°F (430°C) to approximately 500°F (270°C). SEE FIGURE 19–29.

4. The intake air heater may also be activated to warm intake air during regeneration.

TYPES OF DPF REGENERATION

DPF regeneration can be initiated in a number of ways, depending on the vehicle application and operating circumstances. The two main regeneration types are as follows:

Passive regeneration. During normal vehicle operation when driving conditions produce sufficient load and exhaust temperatures, passive DPF regeneration may occur. This passive regeneration occurs without input from the PCM or the driver. A passive regeneration may typically occur while the vehicle is being driven at highway speed or towing a trailer.

Active regeneration. Active regeneration is commanded by the PCM when it determines that the DPF requires it to remove excess soot buildup and conditions for filter regeneration have been met. Active regeneration is usually not noticeable to the driver. The vehicle needs to be driven at speeds above 30 mph for approximately 20 to 30 minutes to

WARNING Tailpipe outlet exhaust temperature will be greater than 572°F (300°C) during service regeneration. To help prevent personal injury or property damage from fire or burns, keep vehicle exhaust away from any object and people.

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complete a full regeneration. During regeneration, the exhaust gases reach temperatures above 1,000°F (550°C). Active regeneration is usually not noticeable to the driver.

ASH LOADING

Regeneration will not burn off ash. Only the particulate matter (PM) is burned off during regeneration. Ash is a noncombustible by-product from normal oil consumption. Ash accumulation in the DPF will eventually cause a restriction in the particulate filter. To service an ash-loaded DPF, the DPF will need to be removed from the vehicle and cleaned or replaced. Low ash content engine oil (API CJ-4) is required for vehicles with the DPF system. The CJ-4 rated oil is limited to 1% ash content.

SELECTIVE CATALYTIC REDUCTION PURPOSE AND FUNCTION

Selective catalytic reduction (SCR) is a method used to reduce NOx emissions by injecting urea into the exhaust stream. Instead of using large amounts of exhaust gas recirculation (EGR), the SCR system uses a urea. Urea is used as a nitrogen fertilizer. It is colorless, odorless, and nontoxic. Urea is called diesel exhaust fluid (DEF) in North America and AdBlue in Europe. SEE FIGURE 19–30.

OUTSIDE AIR

OUTSIDE AIR OXIDATION CATALYST

ENGINE EXHAUST

UREA SCR

NH 3 OXIDE CATALYST

NO X

N2

CO

CO 2

HC

H2 O

PM

FIGURE 19–29 The exhaust is split into two outlets and has slits to help draw outside air in as the exhaust leaves the tailpipe. The end result is cooler exhaust gases exiting the tailpipe.

PM UREA DOUSING SYSTEM

FIGURE 19–31 Urea (diesel exhaust fluid) injection is used to reduce NOx exhaust emissions. It is injected after the diesel oxidation catalyst (DOC) and before the diesel particulate filter (DPF) on this 6.7 liter Ford diesel engine.

Difficult to find local sources of urea

Increased costs to the vehicle owner due to having to refill the urea storage tank

DIESEL EXHAUST SMOKE DIAGNOSIS

FIGURE 19–30 Diesel exhaust fluid costs $3 to $4 a gallon and is housed in a separate container that holds from 5 to 10 gallons, or enough to last until the next scheduled oil change in most diesel vehicles that use SCR. The urea is injected into the catalyst where it sets off a chemical reaction which converts nitrogen oxides (NOx) into nitrogen (N2) and water (H2O). Vehicle manufacturers size the onboard urea storage tank so that it needs to be refilled at about each scheduled oil change or every 7,500 miles (12,000 km). A warning light alerts the driver when the urea level needs to be refilled. If the warning light is ignored and the diesel exhaust fluid is not refilled, current EPA regulations require that the operation of the engine be restricted and may not start unless the fluid is refilled. This regulation is designed to prevent the engine from being operated without the fluid, which, if not, would greatly increase exhaust emissions. SEE FIGURE 19–31.

ADVANTAGES OF SCR Using urea injection instead of large amounts of EGR results in the following advantages.

Potential higher engine power output for the same size engine

Reduced NOx emissions up to 90%

Reduced HC and CO emissions up to 50%

Reduced particulate matter (PM) by 50%

DISADVANTAGES OF SCR

Using urea injection instead of large amounts of EGR results in the following disadvantages.

Onboard storage tank required for the urea

Although some exhaust smoke is considered normal operation for many diesel engines, especially older units, the cause of excessive exhaust smoke should be diagnosed and repaired.

BLACK SMOKE

Black exhaust smoke is caused by incomplete combustion because of a lack of air or a fault in the injection system that could cause an excessive amount of fuel in the cylinders. Items that should be checked include the following:

Fuel specific gravity (API gravity)

Injector balance test to locate faulty injectors using a scan tool

Proper operation of the engine coolant temperature (ECT) sensor

Proper operation of the fuel rail pressure (FRP) sensor

Restrictions in the intake or turbocharger

Engine oil usage

WHITE SMOKE

White exhaust smoke occurs most often during cold engine starts because the smoke is usually condensed fuel droplets. White exhaust smoke is also an indication of cylinder misfire on a warm engine. The most common causes of white exhaust smoke include:

DIESEL PERFORMANCE DIAGNOSIS Diesel engines can be diagnosed using a scan tool in most cases, because most of the pressure sensors values can be displayed. Common faults include:

Hard starting

No start

Extended cranking before starting

Low power

Using a scan tool, check the sensor values in CHART 19–2 to help pin down the source of the problem. Also check the minimum pressures that are required to start the engine if a no-start condition is being diagnosed. SEE FIGURE 19–32.

CHART 19–2 The values can be obtained by using a scan tool and basic test equipment. Always follow the vehicle manufacturer’s recommended procedures.

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FIGURE 19–32 A pressure gauge checking the fuel pressure from the lift pump on a Cummins 6.7 liter diesel.

COMPRESSION TESTING

FIGURE 19–33 A compression gauge that is designed for the higher compression rate of a diesel engine should be used when checking the compression.

A compression test is fundamental for determining the mechanical condition of a diesel engine. Worn piston rings can cause low power and excessive exhaust smoke. To test the compression on a diesel engine, the following will have to be done.

Remove the glow plug (if equipped) or the injector.

Use a diesel compression gauge, as the compression is too high to use a gasoline engine compression gauge.

A diesel engine should produce at least 300 PSI (2,068 kPa) of compression pressure and all cylinders should be within 50 PSI (345 kPa) of each other. SEE FIGURE 19–33.

GLOW PLUG RESISTANCE BALANCE TEST Glow plugs increase in resistance as their temperature increases. All glow plugs should have about the same resistance when checked with an ohmmeter. A similar test of the resistance of the glow plugs can be used to detect a weak cylinder. This test is particularly helpful on a diesel engine that is not computer controlled. To test for even cylinder balance using glow plug resistance, perform the following on a warm engine. 1. Unplug, measure, and record the resistance of all glow plugs. 2. With the wires still removed from the glow plugs, start the engine. 3. Allow the engine to run for several minutes to allow the combustion inside the cylinder to warm the glow plugs.

FIGURE 19–34 A typical pop tester used to check the spray pattern of a diesel engine injector.

INJECTOR POP TESTING

4. Measure the plugs and record the resistance of all glow plugs. 5. The resistance of all glow plugs should be higher than at the beginning of the test. A glow plug that is in a cylinder that is not firing correctly will not increase in resistance as much as the others. 6. Another test is to measure exhaust manifold temperature at each exhaust port using an infrared thermometer or a pyrometer. Misfiring cylinders will run cold.

A pop tester is a device used for checking a diesel injector nozzle for proper spray pattern. The handle is depressed and pop-off pressure is displayed on the gauge. SEE FIGURE 19–34. The spray pattern should be a hollow cone, but will vary depending on design. The nozzle should also be tested for leakage (dripping of the nozzle) while under pressure. If the spray pattern is not correct, then cleaning, repairing, or replacing the injector nozzle may be necessary.

D I E SE L E N G I N E O PE RAT I O N AN D D IA GN OS IS

173

20% opacity

40% opacity

60% opacity

80% opacity

100% opacity

CHART 19–3 An opacity test is sometimes used during a state emission test on diesel engines. TECH TIP Always Use Cardboard to Check for High-Pressure Leaks If diesel fuel is found on the engine, a high-pressure leak could be present. When checking for such a leak, wear protective clothing including safety glasses, a face shield, gloves, and a long-sleeved shirt. Then use a piece of cardboard to locate the high-pressure leak. When a Duramax diesel is running, the pressure in the common rail and injector tubes can reach over 20,000 PSI. At these pressures, the diesel fuel is atomized and cannot be seen but can penetrate the skin and cause personal injury. A leak will be shown as a dark area on the cardboard. When a leak is found, shut off the engine and find the exact location of the leak without the engine running. CAUTION: Sometimes a leak can actually cut through the cardboard, so use extreme care.

DIESEL EMISSION TESTING OPACITY TEST

The most common diesel exhaust emission test used in state or local testing programs is called the opacity test. Opacity means the percentage of light that is blocked by the exhaust smoke.

A 0% opacity means that the exhaust has no visible smoke and does not block light from a beam projected through the exhaust smoke.

A 100% opacity means that the exhaust is so dark that it completely blocks light from a beam projected through the exhaust smoke.

A 50% opacity means that the exhaust blocks half of the light from a beam projected through the exhaust smoke. SEE CHART 19–3.

FIGURE 19–35 The letters on the side of this injector on a Cummins 6.7 liter diesel indicate the calibration number for the injector.

TECH TIP Do Not Switch Injectors In the past, it was common practice to switch diesel fuel injectors from one cylinder to another when diagnosing a dead cylinder problem. However, most high-pressure common rail systems used in new diesels utilize precisely calibrated injectors that should not be mixed up during service. Each injector has its own calibration number.

SEE FIGURE 19–35.

SNAP ACCELERATION TEST In a snap acceleration test, the vehicle is held stationary, with wheel chocks in place and brakes released as the engine is rapidly accelerated to high idle, with the transmission in neutral while smoke emissions are measured. This test is conducted a minimum of six times and the three most consistent measurements are averaged for a final score. ROLLING ACCELERATION TEST

Vehicles with a manual transmission are rapidly accelerated in low gear from an idle speed to a maximum governed RPM while the smoke emissions are measured.

STALL ACCELERATION TEST Vehicles with automatic transmissions are held in a stationary position with the parking brake and service brakes applied while the transmission is placed in “drive.” The accelerator is depressed and held momentarily while smoke emissions are measured. The standards for diesels vary according to the type of vehicle and other factors, but usually include a 40% opacity or less.

REVIEW QUESTIONS 1. What is the difference between direct injection and indirect injection? 2. What are the three phases of diesel ignition? 3. What are the two most commonly used types of diesel injection systems?

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4. Why are glow plugs kept working after the engine starts? 5. What exhaust aftertreatment is needed to achieve exhaust emission standards for vehicles 2007 and newer? 6. What are the advantages and disadvantages of SCR?

6. The diesel injection pump is usually driven by a ______________. a. Gear off the camshaft c. Shaft drive off the crankshaft b. Belt off the crankshaft d. Chain drive off the camshaft 7. Which diesel system supplies high-pressure diesel fuel to all of the injectors all of the time? a. Distributor c. High-pressure common rail b. Inline d. Rotary 8. Glow plugs should have high resistance when ______________ and lower resistance when ______________. a. Cold/warm c. Wet/dry b. Warm/cold d. Dry/wet 9. Technician A says that glow plugs are used to help start a diesel engine and are shut off as soon as the engine starts. Technician B says that the glow plugs are turned off as soon as a flame is detected in the combustion chamber. Which technician is correct? a. Technician A only c. Both Technicians A and B b. Technician B only d. Neither Technician A nor B 10. What part should be removed to test cylinder compression on a diesel engine? a. Injector b. Intake valve rocker arm and stud c. Glow plug d. Glow plug or injector

because it: 1. Transfers heat from the engine to the radiator 2. Protects the engine and the cooling system from rust and corrosion 3. Prevents freezing in cold climates Coolant is a mixture of antifreeze and water. Water is able to absorb more heat per gallon than any other liquid coolant. Under standard conditions, the following occurs.

Water boils at 212°F (100°C) at sea level.

Water freezes at 32°F (0°C).

When water freezes, it increases in volume by about 9%. The expansion of the freezing water can easily crack engine blocks, cylinder heads, and radiators.

A curve depicting freezing point as compared with the percentage of antifreeze mixture is shown in FIGURE 20–1.

FREEZING/BOILING TEMPERATURES

It should be noted that the freezing point increases as the antifreeze concentration is

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175

40 30 20 TEMPERATURE °F

10 0 -10 -20 -30 -40 -50 -60 -70 -80

0 10 20 30 40 50 60 70 80 90 100 PERCENT ANTIFREEZE IN COOLANT

FIGURE 20–1 Graph showing the relationship of the freezing point of the coolant to the percentage of antifreeze used in the coolant. 340 330 320 310 300 TEMPERATURE °F

290 280 270 260 250 240

FIGURE 20–3 Havoline was the first company to make and market OAT coolant. General Motors uses the term DEX-COOL. Regardless of the type of coolant and its color, the only difference among all original equipment coolants is in the additives. This means that about 97% of all coolants are the same. The only difference is in the additive package and color used to help identify the coolant.

FIGURE 20–2 Graph showing how the boiling point of the coolant increases as the percentage of antifreeze in the coolant increases. increased above 60%. The normal mixture is 50% antifreeze and 50% water. Ethylene glycol antifreeze contains:

Anticorrosion additives

Rust inhibitors

Water pump lubricants

At the maximum level of protection, an ethylene glycol concentration of 60% will absorb about 85% as much heat as will water. Ethylene glycol based antifreeze also has a higher boiling point than water. A curve depicting freezing point as compared with the percentage of antifreeze mixture is shown in FIGURE 20–2. If the coolant boils, it vaporizes and does not act as a cooling agent because it is not in liquid form or in contact with the cooling surfaces. All coolants have rust and corrosion inhibitors to help protect the metals in the engine and cooling systems.

COOLANT COMPOSITION All manufacturers recommend the use of ethylene glycol based coolant, which contains:

TYPES OF COOLANT INORGANIC ACID TECHNOLOGY

Inorganic additive technology (IAT) is conventional coolant that has been used for over 50 years. Most conventional green antifreeze contains inorganic salts such as:

Sodium silicate (silicates)

Phosphates

Borates

Silicates have been found to be the cause of erosive wear to water pump impellers. The color of IAT coolant is green. Phosphates in these coolants can cause deposits to form if used with water that is hard (contains minerals). IAT coolants used in new vehicles were phased out in the mid-1990s.

ORGANIC ACID TECHNOLOGY Organic acid technology (OAT) coolant contains ethylene glycol, but does not contain silicates or phosphates. The color of this type of coolant is usually orange. DEX-COOL, developed by Havoline, is just one brand of OAT coolant, which has been used in General Motors vehicles since 1996. SEE FIGURE 20–3. DEX-COOL uses ethylhexanoic acid (2-EH) as a corrosive inhibitor. 2-EH is prone to damage plastics, such as Nylon 6.6 used in intake manifold gaskets and radiators. Other brands of OAT coolant that are also orange but do not contain 2-EH include:

Ethylene glycol (EG): 47%

Water: 50%

Zerex G30 or G05 OAT

Additives: 3%

Peak Global OAT

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?

FREQUENTLY ASKED QUESTION

What Is a “G” Coolant? The “G” coolants come from the trade name Glysantin of BASF in Europe and Valvoline (Zerex) in the United States. The following is a summary of the types listed by G number. • G05: different from DEX-COOL in certain amounts of additives • G30 and G34: nonsilicate and phosphate free • G11: blue VW used before 1997 • G12: pink/red VW 1997⫹ (purple VW 2003⫹) • HOAT formulation • Phosphate free • G48: low silicate and phosphate free • Blue • Nitrates, amines, phosphate (NAP) free

These coolants are usually available in premix (with water) and pure coolant containers.

HYBRID ORGANIC ACID TECHNOLOGY

A newer variation of this technology is called hybrid organic acid technology (HOAT). It is similar to the OAT-type antifreeze as it uses organic acid salts (carboxylates) that are not abrasive to water pumps, yet provide the correct pH. The pH of the coolant is usually above 11. A pH of 7 is neutral, with lower numbers indicating an acidic solution and higher numbers indicating an alkaline solution. If the pH is too high, the coolant can cause scaling and reduce the heat transferability of the coolant. If the pH is too low, the resulting acidic solution could cause corrosion of the engine components exposed to the coolant. HOAT coolants can be green, orange, yellow, gold, pink, red, or blue. Samples of HOAT coolants include:

VW/Audi pink. Contains some silicates and an organic acid, and is phosphate free

Mercedes/Ford yellow. Contains low amounts of silicate and no phosphate

Ford yellow. Contains low silicate, no phosphate, and is dyed yellow for identification

Honda blue. Contains a special coolant with just one organic acid

European/Korean blue. Contains low silicates and no phosphates

Asian red. Contains no silicates but has some phosphate

PHOSPHATE HYBRID ORGANIC ACID TECHNOLOGY Phosphate hybrid organic acid technology (PHOAT) is used in Mazda-based Fords (2008⫹), same as Mazda FL-22, and is ethylene glycol based. This coolant is available in a 55% coolant/45% water premix. SEE FIGURE 20–4.

Concentration: 55%

Boiling point (with 15 PSI pressure cap): 270°F (132°C)

Freezing point: ⫺47°F (⫺44°C)

Color: Dark green

Embittered (made to taste bitter so animals will not drink it)

The use of PHOAT coolant in these engines is required to be assured of proper protection of the material used in the engine. It

FIGURE 20–4 Coolant used in Fords that use Mazda engines and in Mazda vehicles. It requires the use of a PHOAT coolant which is dark green.

?

FREQUENTLY ASKED QUESTION

What Is “Pet Friendly” Antifreeze? Conventional ethylene glycol antifreeze used by all vehicle manufacturers is attractive to pets and animals because it has a sweet taste. Ethylene glycol is fatal to any animal if swallowed, so any spill should be cleaned up quickly. There are two types of coolant that are safer for use around pets than the conventional type. • Propylene glycol (PG). This type of antifreeze is less attractive to pets and animals because it is not as sweet, but it is still harmful if swallowed. This type of coolant, including the Sierra brand, should not be mixed with any other ethylene glycol based coolant. CAUTION: Some vehicle manufacturers do not recommend the use of propylene glycol coolant. Check the recommendation in the owner manual or service information before using it in a vehicle. • Embittered coolant. This coolant has a small amount of a substance that makes it taste bitter and therefore not appealing to animals. The embittering agent used in ethylene glycol (EG) antifreeze is usually denatonium benzoate, added at the rate of 30 ppm. Oregon and California require all coolant sold in these states since 2004 to be embittered. SEE FIGURE 20–5.

is also only available in premix containers to ensure that the water used meets specifications.

UNIVERSAL COOLANT

Universal coolant is usually a hybrid organic acid technology (HOAT), with extended life, and a lowsilicate, phosphate-free antifreeze/coolant. It can be used in many vehicles, but cannot meet the needs for engines requiring a silicatefree formulation.

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?

FREQUENTLY ASKED QUESTION

What Makes Some Water Bad for Coolant? City water is treated with chloride, which, if the levels are high enough, can cause corrosion problems when used in coolants. Well water may contain iron or other minerals that can affect the coolant and may increase the corrosion or cause electrolysis. Due to the fact that the water quality is often unknown and could affect the engine, many vehicle manufacturers are specifying the use of premixed coolant. In pre-mix coolant, the water is usually demineralized and meets the standards for use in coolant.

?

FIGURE 20–5 Not all embittered coolant is labeled embittered.

FREQUENTLY ASKED QUESTION

Why Is Most Coolant 50/50 with Water? REAL WORLD FIX

According to the freezing point, it appears that the lowest freezing point of coolant is achieved when 70% antifreeze is used with 30% water. While the freezing temperature is lower, the high concentrate of antifreeze reduces the heat transferability of the coolant. Therefore, most vehicle manufacturers specify a 50/50 mixture of antifreeze and water to achieve the best balance between freeze protection and heat conductivity.

If 50% Is Good, 100% Must Be Better A vehicle owner said that the cooling system of his vehicle would never freeze or rust. He said that he used 100% antifreeze (ethylene glycol) instead of a 50/50 mixture with water. However, after the temperature dropped to ⫺20°F (⫺29°C), the radiator froze and cracked. (Pure antifreeze freezes at about 0°F [⫺18°C]). After thawing, the radiator had to be repaired. The owner was lucky that the engine block did not also crack. For best freeze protection with good heat transfer, use a 50/50 mixture of antifreeze and water. A 50/50 mixture of antifreeze and water is the best compromise between temperature protection and the heat transfer that is necessary for cooling system operation. Do not exceed 70% antifreeze (30% water). As the percentage of antifreeze increases, the boiling temperature increases, and freezing protection increases (up to 70% antifreeze), but the heat transfer performance of the mixture decreases.

WATER INTRODUCTION

Water is half of the coolant and can have an effect on the corrosion protection of coolant due to variations in its quality, which is often unknown. As a result, many vehicle manufacturers, such as Honda and Toyota, are specifying the use of premix coolants only. The main reason is that not only can the water/coolant ratio be maintained, but also the quality of the water can be controlled.

PROPERTIES Water is about half of the coolant and is used because of the following qualities. 1. It is inexpensive.

COOLANT FREEZING/ BOILING TEMPERATURES FREEZING POINT An antifreeze and water mixture is an example wherein the freezing point differs from the freezing point of either pure antifreeze or pure water.

Freezing Point

Pure water

32°F (0°C)

Pure antifreeze*

0°F (⫺18°C)

50/50 mixture

⫺34°F (⫺37°C)

70% antifreeze/30% water

⫺84°F (⫺64°C)

*Pure antifreeze is usually 95% ethylene glycol, 2% to 3% water, and 2% to 3% additives.

Depending on the exact percentage of water used, antifreeze (not premixed), as sold in containers, freezes at about 0°F (⫺18°C). Premixed coolant will freeze at about ⫺34°F (⫺37°C).

BOILING POINT The boiling point of antifreeze and water is also a factor of mixture concentrations.

2. It is an efficient heat exchange fluid because of its excellent thermal conductivity (the ability of a material to conduct heat).

Boiling Point at Sea Level

Boiling Point with 15 PSI Pressure Cap

Pure water

212°F (100°C)

257°F (125°C)

4. The boiling point is 212°F (100°C) (at sea level).

50/50 mixture

218°F (103°C)

265°F (130°C)

5. The freezing point is 32°F (0°C).

70/30 mixture

225°F (107°C)

276°F (136°C)

3. It has good specific heat capacity, meaning it takes more heat energy to increase the temperature, versus one with low specific heat capacity.

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If the engine is overheating and the hydrometer reading is near ⫺50°F (⫺60°C), suspect that pure 100% antifreeze is present. For best results, the coolant should have a freezing point lower than ⫺20°F (⫺29°C) and a boiling point above 234°F (112°).

COOLANT TESTING Normal coolant tests include:

Visual inspection. Coolant should be clean and bright.

Freeze/boiling point. A high freezing point or low boiling point indicates dilution (too much water).

pH. The wrong pH indicates buffer loss, which is used to help maintain the pH level.

Coolant voltage. A high voltage indicates the wrong pH or a stray current flow. Various methods are used to test coolant.

HYDROMETER TESTING

Coolant can be checked using a coolant hydrometer. The hydrometer measures the density of the coolant. The higher the density is, the more concentration of antifreeze in the water. Most coolant hydrometers read the freezing and boiling points of the coolant. SEE FIGURE 20–6.

REFRACTOMETER

A refractometer is a tester used to test the freezing point of coolant by placing a few drops of coolant on the prism surface. The technician then holds the unit up to light and looks through the eyepiece for the location of the shadow on the display. A refractometer measures the extent to which light is bent (refracted) to determine the index of refraction of a liquid sample. The refractive index is commonly used for the following:

To identify or confirm the identity of a sample coolant

To determine the purity of a coolant by comparing its refractive index to the value for the pure substance

To determine the concentration of a solute in a solution by comparing the solution’s refractive index to a standard curve

SEE FIGURE 20–7.

TECH TIP Ignore the Wind Chill Factor

FIGURE 20–6 Checking the freezing temperature of the coolant using a hydrometer.

-84

The wind chill factor is a temperature that combines the actual temperature and the wind speed to determine the overall heat loss effect on open skin. Because it is the heat loss factor for open skin, the wind chill temperature is not to be considered when determining antifreeze protection levels. Although moving air makes it feel colder, the actual temperature is not changed by the wind, and the engine coolant will not be affected by the wind chill. If you are not convinced, try placing a thermometer in a room and wait until a stable reading is obtained. Now turn on a fan and have the air blow across the thermometer. The temperature will not change.

1. PLACE A FEW DROPS OF THE SAMPLE FLUID ON THE MEASURING PRISM AND CLOSE THE COVER

-80 -70

1.400

-60

1.350

-50 -40 -34 -30

1.300 1.250 1.200 1.150

1.100

G o o d

-60 -50 -40 -30 -20 -10 -5

-20 F a

i

R e c h a r g e

BATTERY CHARGE

r

-10 -5 0

0 +5 +10

+5 +10

+15

2. HOLD UP TO A LIGHT AND READ THE SCALE

+15 +20 +20 +25

+25

+32

+32 ETHYLENE GLYCOL

˚F

PROPYLENE GLYCOL

FIGURE 20–7 Using a refractometer is an accurate method to check the freezing point of coolant.

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BI-METAL CORROSION

ELECTRONS

ELECTROLYTE

ANODE

FIGURE 20–8 A meter that measures the actual pH of the coolant can be used for all coolants, unlike many test strips that cannot be used to test the pH of red or orange coolants.

PH

The term pH comes from a French word, meaning “power of hydrogen,” and is a measure of acidity or alkalinity of a solution.

Less than 7 pH is considered acidic.

Greater than 7 pH is considered alkaline.

CATHODE

(MORE REACTIVE METAL)

(LESS REACTIVE METAL)

FIGURE 20–9 Galvanic activity is created by two dissimilar metals in contact with a liquid, in this case coolant.

The pH of new coolant varies according to the type of coolant used. Typical pH values for new coolant include: IAT: 9 to 10.5 new OAT: 7.5 to 8.5 new (G30 and G34 designations) HOAT: 7.5 to 8.5 new (G05, G48, G11, or G12 designation) PHOAT: 7.5 to 8.5 new When testing for pH, use either a test strip or a pH meter. If using a test strip be sure that it is calibrated to test the type of coolant being used in the vehicle. Used coolant pH readings are usually lower than when the coolant is new and range from between 7.5 and 10 for IAT and lower for used OAT, HOAT, and PHOAT coolants. For best results use a pH tester that measures the actual pH of the coolant. SEE FIGURE 20–8.

GALVANIC ACTIVITY

Galvanic activity is the flow of an electrical current as a result of two different metals in a liquid, which acts like a battery. Galvanic activity does not require an outside source of voltage. The two different metals, usually iron and aluminum, become the plates of the battery and the coolant is the electrolyte. The higher the electrical conductivity of the coolant, the greater is the amount of corrosion. SEE FIGURE 20–9.

ELECTROLYSIS

Electrolysis requires the use of an outside voltage source. The source is usually due to a poor electrical ground connection.

Electrical flow through the cooling system may cause metal to flow into the coolant.

This metal transfer can eat holes in a heater core or radiator.

Electrolysis holes will usually start from the inside and have a dark coloration.

FIGURE 20–10 A test strip can be used to determine the pH and percentage of glycol of the coolant. The percentage of glycol determines the freezing and boiling temperatures, as shown on the bottle that contains the test strips.

STEP 4

Read the meter. If the voltage is above 0.5 V, this indicates excessive galvanic activity. Normal readings should be less than 0.2 V (200 mV). Flush and refill the cooling system.

STEP 5

To test for excessive electrolysis, start the engine and turn on all electrical accessories, including the headlights on high beam.

STEP 6

Read the voltmeter. If the reading is higher than 0.5 V, check for improper body ground wires or connections. Normal readings should be less than 0.3 V (300 mV).

TEST STRIP TESTING

Test strips can be used to check one

or more of the following:

TESTING FOR GALVANIC ACTIVITY AND ELECTROLYSIS A voltmeter set to read DC volts is used to test for galvanic activity and electrolysis. To check for excessive voltage caused by galvanic activity or electrolysis, perform the following steps. STEP 1

Allow the engine to cool and then carefully remove the pressure cap from the radiator.

STEP 2

Set the voltmeter to DC volts and connect the black meter lead to a good engine ground.

STEP 3

Place the red meter lead into the coolant.

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Freeze point

Boiling point

Level of pH

Test strips will change color when they are dipped into the coolant, and the color change is compared to the container. Test strips are fairly accurate, easy to use, and inexpensive. For best results, use test strips that are new and have been stored in a sealed bottle. Using older test strips may affect the accuracy. SEE FIGURE 20–10.

COOLANT REPLACEMENT ISSUES INTERVALS

Coolant should be replaced according to the vehicle manufacturer’s recommended interval.

For most new vehicles using OAT or HOAT type coolant, this interval may be every five years or 150,000 miles (241,000 km), whichever occurs first.

Japanese brand vehicles usually have a replacement interval of three years or 36,000 miles (58,000 km), whichever occurs first.

If the coolant is changed from a long life to a conventional IAT coolant, the replacement interval needs to be changed to every two years or 24,000 miles (39,000 km), whichever occurs first.

PASSIVATION

Passivation is a chemical reaction that takes place between coolant additives and the metal that it protects. This means that a chemical barrier is created between the coolant and

the metals of the engine. When changing coolants, passivation can take from a few days to a few weeks.

Each chemical package does its own passivation.

If you change chemical packages, passivation has to start over.

Therefore, because of passivation concerns, most experts agree that for best results do not change types of coolants. Always use what the vehicle manufacturer recommends. Always check service information for the exact recommended replacement interval for the vehicle being serviced.

RECYCLING COOLANT

Coolant (antifreeze and water) should be recycled. Used coolant may contain heavy metals, such as lead, aluminum, and iron, which are absorbed by the coolant during its use in the engine. Recycle machines filter out these metals and dirt and reinstall the depleted acids. The recycled coolant, restored to be like new, can be reinstalled into the vehicle. CAUTION: Most vehicle manufacturers warn that coolant should not be reused unless it is recycled and the acids restored. However, Mercedes lifetime coolant is very expensive, and according to Mercedes can be drained, filtered, and reused.

REVIEW QUESTIONS 1. What types of coolant are used in vehicles? 2. Why is a 50/50 mixture of antifreeze and water commonly used as a coolant?

4. What are some of the heavy metals that can be present in used coolant? 5. What is the difference between galvanic activity and electrolysis?

7. DEX-COOL is ______________. a. Propylene glycol b. Ethylene glycol c. Is silicate and phosphate free d. Both b and c 8. Two technicians are discussing testing coolant for proper pH. Technician A says that coolant has a pH above 7 when new and becomes lower with use in an engine. Technician B says that OAT and HOAT coolants have a lower pH when new compared to the old green IAT coolant. Which technician is correct? a. Technician A only c. Both Technicians A and B b. Technician B only d. Neither Technician A nor B 9. Reusing old coolant is generally not approved by vehicle manufacturers except ______________. a. General Motors c. Chrysler b. Ford d. Mercedes 10. A voltmeter was used to check the coolant and a reading of 0.2 volt with the engine off was measured. A reading of 0.8 volt was measured with the engine running and all electrical accessories turned on. Technician A says that the coolant should be flushed to solve the galvanic activity. Technician B says that the ground wires and connections should be inspected and repaired to solve the electrolysis problem. Which technician is correct? a. Technician A only c. Both Technicians A and B b. Technician B only d. Neither Technician A nor B

Satisfactory cooling system operation depends on the design and operating conditions of the system. The design is based on heat output of the engine, radiator size, type of coolant, size of water pump (coolant pump), type of fan, thermostat, and system pressure. The cooling system must allow the engine to warm up to the required operating temperature as rapidly as possible and then maintain that temperature. Peak combustion temperatures in the engine run from 4,000°F to 6,000°F (2,200°C to 3,300°C). The combustion temperatures will average between 1,200°F and 1,700°F (650°C and 925°C). Continued temperatures as high as this would weaken engine parts, so heat must be removed from the engine. The cooling system keeps the head and cylinder walls at a temperature that is within the range for maximum efficiency. The cooling system removes about one-third of the heat created in the engine. Another third escapes to the exhaust system. SEE FIGURE 21–1.

LOW-TEMPERATURE ENGINE PROBLEMS Engine operating temperatures must be above a minimum temperature for proper engine operation. If the coolant temperature does not reach the specified temperature as determined by the thermostat, then the following engine-related faults can occur.

A P0128 diagnostic trouble code (DTC) can be set. This code indicates “coolant temperature below thermostat regulating temperature,” which is usually caused by a defective thermostat staying open or partially open. Moisture created during the combustion process can condense and flow into the oil. For each gallon of fuel used, moisture equal to a gallon of water is produced. The condensed moisture combines with unburned hydrocarbons and additives to form carbonic acid, sulfuric acid, nitric acid, hydrobromic acid, and hydrochloric acid.

To reduce cold engine problems and to help start engines in cold climates, most manufacturers offer block heaters as an option. These

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EXHAUST 1,500° COOLANT 4,500° COOLANT

PISTON

FIGURE 21–1 Typical combustion and exhaust temperatures.

TECH TIP Overheating Can Be Expensive A faulty cooling system seems to be a major cause of engine failure. Engine rebuilders often have nightmares about seeing their rebuilt engine placed back in service in a vehicle with a clogged radiator. Most engine technicians routinely replace the water pump and all hoses after an engine overhaul or repair. The radiator should also be checked for leaks and proper flow whenever the engine is repaired or replaced. Overheating is one of the most common causes of engine failure.

BYPASS PIPE

WATER JACKET

RADIATOR

COMBUSTION CHAMBER WATER JACKET CORE PLUG

CORE PLUG FAN

THERMOSTAT WATER PUMP

FIGURE 21–3 Coolant flow through a typical engine cooling system.

COOLANT

FIGURE 21–2 Coolant circulates through the water jackets in the engine block and cylinder head.

block heaters are plugged into household current (110 volts AC) and the heating element warms the coolant.

HIGH-TEMPERATURE ENGINE PROBLEMS Maximum temperature limits are required to protect the engine. Higher than normal temperatures can cause the following engine-related issues.

High temperatures will oxidize the engine oil producing hard carbon and varnish. The varnish will cause the hydraulic valve lifter plungers to stick. Higher than normal temperatures will also cause the oil to become thinner (lower viscosity than normal). Thinned oil will also get into the combustion chamber by going past the piston rings and through valve guides to cause excessive oil consumption. The combustion process is very sensitive to temperature. High coolant temperatures raise the combustion temperatures to a point that may cause detonation (also called spark knock or ping) to occur.

COOLING SYSTEM OPERATION PURPOSE AND FUNCTION Coolant flows through the engine, where it picks up heat. It then flows to the radiator, where the heat is given up to the outside air. The coolant continually recirculates through the cooling system, as illustrated in FIGURES 21–2 AND 21–3. COOLING SYSTEM OPERATION The temperature of the coolant rises as much as 15°F (8°C) as it goes through the engine and cools as it goes through the radiator. The coolant flow rate may be as high as 1 gallon (4 liters) per minute for each horsepower the engine produces. Hot coolant comes out of the thermostat housing on the top of the engine on most engines. The engine coolant outlet is connected

to the radiator by the upper radiator hose and clamps. The coolant in the radiator is cooled by air flowing through the radiator. As the coolant moves through the radiator, it cools. The cooler coolant leaves the radiator through an outlet and the lower radiator hose, and then flows to the inlet side of the water pump, where it is recirculated through the engine. NOTE: Some newer engine designs such as Chrysler’s 4.7 liter V-8 and General Motor’s 4.8, 5.3, 5.7, and 6.0 liter V-8s place the thermostat on the inlet side of the water pump. As the cooled coolant hits the thermostat, the thermostat closes until the coolant temperature again causes it to open. Placing the thermostat in the inlet side of the water pump therefore reduces the rapid temperature changes that could cause stress in the engine, especially if aluminum heads are used with a cast iron block. Radiators are designed for the maximum rate of heat transfer using minimum space. Cooling airflow through the radiator is aided by a belt- or electric motor–driven cooling fan.

THERMOSTATS PURPOSE AND FUNCTION There is a normal operating temperature range between low-temperature and high-temperature extremes. The thermostat controls the minimum normal temperature. The thermostat is a temperature-controlled valve placed at the engine coolant outlet on most engines. THERMOSTAT OPERATION An encapsulated wax-based plastic pellet heat sensor is located on the engine side of the thermostatic valve. As the engine warms, heat swells the heat sensor. SEE FIGURE 21–4. A mechanical link, connected to the heat sensor, opens the thermostat valve. As the thermostat begins to open, it allows some coolant to flow to the radiator, where it is cooled. The remaining part of the coolant continues to flow through the bypass, thereby bypassing the thermostat and flowing back through the engine. SEE FIGURE 21–5. The rated temperature of the thermostat indicates the temperature at which the thermostat starts to open. The thermostat is fully

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SPRING

PISTON

UPPER HOUSING

THERMOSTAT TEMPERATURE RATING

STARTS TO OPEN

FULLY OPEN

180°F

180°F

200°F

195°F

195°F

215°F

CHART 21–1 The temperature of the coolant depends on the rating of the thermostat.

LOWER HOUSING

COPPER CUP

WAX PELLET

FIGURE 21–4 A cross section of a typical wax-actuated thermostat showing the position of the wax pellet and spring.

COOLANT COLD FLOWS TO ENGINE THERMOSTAT CLOSED

FIGURE 21–6 A thermostat stuck in the open position caused the engine to operate too cold. If a thermostat is stuck closed, this can cause the engine to overheat.

BYPASS PASSAGE

(a) COOLANT HOT FLOWS TO RADIATOR THERMOSTAT OPEN

FIGURE 21–7 This internal bypass passage in the thermostat housing directs cold coolant to the water pump.

(b)

FIGURE 21–5 (a) When the engine is cold, the coolant flows through the bypass. (b) When the thermostat opens, the coolant can flow to the radiator.

open at about 20°F higher than its opening temperature. SEE CHART 21–1. If the radiator, water pump, and coolant passages are functioning correctly, the engine should always be operating within the opening and fully open temperature range of the thermostat. SEE FIGURE 21–6.

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NOTE: A bypass around the closed thermostat allows a small part of the coolant to circulate within the engine during warm-up. It is a small passage that leads from the engine side of the thermostat to the inlet side of the water pump. It allows some coolant to bypass the thermostat even when the thermostat is open. The bypass may be cast or drilled into the engine and pump parts. SEE FIGURES 21–7 AND 21–8. The bypass aids in uniform engine warm-up. Its operation eliminates hot spots and prevents the building of excessive coolant pressure in the engine when the thermostat is closed.

TECH TIP Do Not Take Out the Thermostat! Some vehicle owners and technicians remove the thermostat in the cooling system to “cure” an overheating problem. In some cases, removing the thermostat can cause overheating rather than stop it. This is true for three reasons.

FIGURE 21–8 A cutaway of a small block Chevrolet V-8 showing the passage from the cylinder head through the front of the intake manifold to the thermostat.

THERMOSTAT TESTING

There are three basic methods used to check the operation of the thermostat. 1. Hot water method. If the thermostat is removed from the vehicle and is closed, insert a 0.015 in. (0.4 mm) feeler gauge in the opening so that the thermostat will hang on the feeler gauge. The thermostat should then be suspended by the feeler gauge in a container of water or coolant along with a thermometer. The container should be heated until the thermostat opens enough to release and fall from the feeler gauge. The temperature at which the thermostat falls is the opening temperature of the thermostat. If it is within 5°F (4°C) of the temperature stamped on the thermostat, the thermostat is satisfactory for use. If the temperature difference is greater, the thermostat should be replaced. SEE FIGURE 21–9. 2. Infrared thermometer method. An infrared thermometer (also called a pyrometer) can be used to measure the temperature of the coolant near the thermostat. The area on the engine side of the thermostat should be at the highest temperature that exists in the engine. A properly operating cooling system should cause the pyrometer to read as follows: As the engine warms, the temperature reaches near thermostat opening temperature. As the thermostat opens, the temperature drops just as the thermostat opens, sending coolant to the radiator. As the thermostat cycles, the temperature should range between the opening temperature of the thermostat and 20°F (11°C) above the opening temperature. NOTE: If the temperature rises higher than 20°F (11°C) above the opening temperature of the thermostat, inspect the cooling system for a restriction or low coolant flow. A clogged radiator could also cause the excessive temperature rise. 3. Scan tool method. A scan tool can be used on many vehicles to read the actual temperature of the coolant as detected by the engine coolant temperature (ECT) sensor. Although the sensor or the wiring to and from the sensor may be defective, at least the scan tool can indicate what the computer “thinks” is the engine coolant temperature.

1. Without a thermostat the coolant can flow more quickly through the radiator. The thermostat adds some restriction to the coolant flow, and therefore keeps the coolant in the radiator longer. This also allows additional time for the heat transfer between the hot engine parts and the coolant. The presence of the thermostat thus ensures a greater reduction in the coolant temperature before it returns to the engine. 2. Heat transfer is greater with a greater difference between the coolant temperature and air temperature. Therefore, when coolant flow rate is increased (no thermostat), the temperature difference is reduced. 3. Without the restriction of the thermostat, much of the coolant flow often bypasses the radiator entirely and returns directly to the engine. If overheating is a problem, removing the thermostat will usually not solve the problem. Remember, the thermostat controls the temperature of the engine coolant by opening at a certain temperature and closing when the temperature falls below the minimum rated temperature of the thermostat.

THERMOMETER FEELER GAUGE

HEATER

FIGURE 21–9 Checking the opening temperature of a thermostat.

THERMOSTAT REPLACEMENT

Two important things about

a thermostat include: 1. An overheating engine may result from a faulty thermostat. 2. An engine that does not get warm enough always indicates a faulty thermostat.

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TOP TANK

RADIATOR CAP

TUBES

COOLANT FLOW

BOT TOM TANK

FIGURE 21–10 Some thermostats are an integral part of the housing. This thermostat and radiator hose housing is serviced as an assembly. Some thermostats snap into the engine radiator fill tube underneath the pressure cap.

TRANSMISSION OIL COOLER

TUBES

RADIATOR CAP

COOLING FIN

COOLANT FLOW FINS

TUBES TRANSMISSION OIL COOLER

FIGURE 21–11 The tubes and fins of the radiator core.

FIGURE 21–12 A radiator may be either a down-flow or a crossflow type. To replace the thermostat, coolant will have to be drained from the radiator drain petcock to lower the coolant level below the thermostat. It is not necessary to completely drain the system. The hose should be removed from the thermostat housing neck and then the housing removed to expose the thermostat. SEE FIGURE 21–10. The gasket flanges of the engine and thermostat housing should be cleaned, and the gasket surface of the housing must be flat. The thermostat should be placed in the engine with the sensing pellet toward the engine. Make sure that the thermostat position is correct, and install the thermostat housing with a new gasket or O-ring. CAUTION: Failure to set the thermostat into the recessed groove will cause the housing to become tilted when tightened. If this happens and the housing bolts are tightened, the housing will usually crack, creating a leak. The upper hose should then be installed and the system refilled. Install the correct size of radiator hose clamp.

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RADIATORS TYPES

The two types of radiator cores in common use in most vehicles are:

Serpentine fin core

Plate fin core

In each of these types, the coolant flows through oval-shaped core tubes. Heat is transferred through the tube wall and soldered joint to cooling fins. The fins are exposed to the air that flows through the radiator, which removes heat from the radiator and carries it away. SEE FIGURES 21–11 AND 21–12. Older automobile radiators were made from yellow brass. Since the 1980s, most radiators have been made from aluminum with nylon-reinforced plastic side tanks. These materials are corrosion resistant, have good heat transferability, and are easily formed.

TRANSMISSION FLUID COOLER

TECH TIP Working Better Under Pressure A problem that sometimes occurs with a high-pressure cooling system involves the water pump. For the pump to function, the inlet side of the pump must have a lower pressure than its outlet side. If inlet pressure is lowered too much, the coolant at the pump inlet can boil, producing vapor. The pump will then spin the coolant vapors and not pump coolant. This condition is called pump cavitation. Therefore, a radiator cap could be the cause of an overheating problem. A pump will not pump enough coolant if not kept under the proper pressure for preventing vaporization of the coolant.

FLUID LINES CROSSFLOW RADIATOR

FIGURE 21–13 Many vehicles equipped with an automatic transmission use a transmission fluid cooler installed in one of the radiator tanks.

Core tubes are made from 0.0045 to 0.012 in. (0.1 to 0.3 mm) sheet brass or aluminum, using the thinnest possible materials for each application. The metal is rolled into round tubes and the joints are sealed with a locking seam. The two basic designs of radiators include: 1. Down-flow radiators. This design was used mostly in older vehicles, where the coolant entered the radiator at the top and flowed downward, exiting the radiator at the bottom. 2. Cross-flow radiators. Most radiators use a cross-flow design, where the coolant flows from one side of the radiator to the opposite side.

PRESSURE CAPS OPERATION On most radiators the filler neck is fitted with a pressure cap. The cap has a spring-loaded valve that closes the cooling system vent. This causes cooling pressure to build up to the pressure setting of the cap. At this point, the valve will release the excess pressure to prevent system damage. Engine cooling systems are pressurized to raise the boiling temperature of the coolant.

The boiling temperature will increase by approximately 3°F (1.6°C) for each pound of increase in pressure. At sea level, water will boil at 212°F (100°C). With a 15 PSI (100 kPa) pressure cap, water will boil at 257°F (125°C), which is a maximum operating temperature for an engine.

FUNCTIONS

The specified coolant system temperature serves

two functions.

HOW RADIATORS WORK

The main limitation of heat transfer in a cooling system is in the transfer from the radiator to the air. Heat transfers from the water to the fins as much as seven times faster than heat transfers from the fins to the air, assuming equal surface exposure. The radiator must be capable of removing an amount of heat energy approximately equal to the heat energy of the power produced by the engine. Each horsepower is equivalent to 42 BTUs (10,800 calories) per minute. As the engine power is increased, the heat-removing requirement of the cooling system is also increased. With a given frontal area, radiator capacity may be increased by increasing the core thickness, packing more material into the same volume, or both. The radiator capacity may also be increased by placing a shroud around the fan so that more air will be pulled through the radiator. NOTE: The lower air dam in the front of the vehicle is used to help direct the air through the radiator. If this air dam is broken or missing, the engine may overheat, especially during highway driving due to the reduced airflow through the radiator. When a transmission oil cooler is used in the radiator, it is placed in the outlet tank, where the coolant has the lowest temperature. SEE FIGURE 21–13.

1. It allows the engine to run at an efficient temperature, close to 200°F (93°C), with no danger of boiling the coolant. 2. The higher the coolant temperature, the more heat the cooling system can transfer. The heat transferred by the cooling system is proportional to the temperature difference between the coolant and the outside air. This characteristic has led to the design of small, high-pressure radiators that are capable of handling large quantities of heat. For proper cooling, the system must have the right pressure cap correctly installed. A vacuum valve is part of the pressure cap and is used to allow coolant to flow back into the radiator when the coolant cools down and contracts. SEE FIGURE 21–14. NOTE: The proper operation of the pressure cap is especially important at high altitudes. The boiling point of water is lowered by about 1°F for every 550 ft increase in altitude. Therefore, in Denver, Colorado (altitude 5,280 ft), the boiling point of water is about 202°F, and at the top of Pike’s Peak in Colorado (14,110 ft) water boils at 186°F.

METRIC RADIATOR CAPS

According to the SAE Handbook, all radiator caps must indicate their nominal (normal) pressure rating. Most original equipment radiator caps are rated at about 14 to 16 PSI (97 to 110 kPa).

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VACUUM VALVE

OVERFLOW TUBE – COOLANT FLOW FROM RECOVE RY TANK

PRESSURE VALVE

OVERFLOW TUBE – COOLANT FLOW TO RECOVE RY TANK

VACUUM VALVE OPERATION

PRESSURE SPRING

GASKET

PRESSURE VALVE OPERATION

FIGURE 21–14 The pressure valve maintains the system pressure and allows excess pressure to vent. The vacuum valve allows coolant to return to the system from the recovery tank. However, many vehicles manufactured in Japan or Europe use radiator pressure indicated in a unit called a bar. One bar is the pressure of the atmosphere at sea level, or about 14.7 PSI. The conversions in CHART 21–2 can be used when replacing a radiator cap, to make certain it matches the pressure rating of the original. NOTE: Many radiator repair shops use a 7 PSI (0.5 bar) radiator cap on a repaired radiator. A 7 PSI cap can still provide boil protection of 21°F (3°F ⴛ 7 PSI ⴝ 21°F) above the boiling point of the coolant. For example, if the boiling point of the antifreeze coolant is 223°F, then 21°F is added for the pressure cap, and boilover will not occur until about 244°F (223°F ⴙ 21°F ⴝ 244°F). Even though this lower pressure radiator cap provides some protection and will also help protect the radiator repair, the coolant can still boil before the “hot” dash warning light comes on and, therefore, should not be used. In addition, the lower pressure in the cooling system could cause cavitation to occur and damage the water pump. For best results, always follow the vehicle manufacturer’s recommended radiator cap.

BAR OR ATMOSPHERES

POUNDS PER SQUARE INCH (PSI)

1.1

16

1.0

15

0.9

13

0.8

12

0.7

10

0.6

9

0.5

7

CHART 21–2 Comparison showing the metric pressure as shown on the top of the cap to pounds per square inch (PSI).

THERMOSTAT HEATER CONTROL VALVE

COOLANT RECOVERY SYSTEMS PURPOSE AND FUNCTION

Excess pressure usually forces some coolant from the system through an overflow. Most cooling systems connect the overflow to a plastic reservoir to hold excess coolant while the system is hot. SEE FIGURE 21–15. When the system cools, the pressure in the cooling system is reduced and a partial vacuum forms. This vacuum pulls the coolant from the plastic container back into the cooling system, keeping the system full. Because of this action, the system is called a coolant recovery system. A vacuum valve allows coolant to reenter the system as the system cools so that the radiator parts will not collapse under the partial vacuum.

SURGE TANK

Some vehicles use a surge tank, which is located at the highest level of the cooling system and holds about 1 quart (1 liter) of coolant. A hose attaches to the bottom of the surge tank to the inlet side of the water pump. A smaller bleed hose attaches

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PLASTIC EXPANSION TANK

HEATER CORE WATER PUMP RADIATOR CAP

FULL ADD

RADIATOR

CLOSED LINE CONNECTING RADIATOR TO EXPANSION TANK

FIGURE 21–15 The level in the coolant recovery system raises and lowers with engine temperature.

to the side of the surge tank to the highest point of the radiator. The bleed line allows some coolant circulation through the surge tank, and air in the system will rise below the radiator cap and be forced from the system if the pressure in the system exceeds the rating of the radiator cap. SEE FIGURE 21–16.

SCROLL

FIGURE 21–16 Some vehicles use a surge tank, which is located at the highest level of the cooling system, with a radiator cap.

FIGURE 21–17 Coolant flow through the impeller and scroll of a coolant pump for a V-type engine.

REAL WORLD FIX The Collapsed Radiator Hose Story An automotive student asked the automotive instructor what brand of radiator hose is the best. Not knowing exactly what to say, the instructor asked if there was a problem with the brand hose used. The student had tried three brands and all of them collapsed when the engine cooled. The instructor then explained that the vehicle needed a new pressure cap and not a new upper radiator hose. The student thought that because the lower hose did not collapse that the problem had to be a fault with the hose. The instructor then explained that the lower radiator hose has a spring inside to keep the lower hose from collapsing due to the lower pressure created at the inlet to the water pump. The radiator cap was replaced and the upper radiator hose did not collapse when the engine cooled.

WATER PUMPS OPERATION

The water pump (also called a coolant pump) is driven by one of two methods.

Crankshaft belt

Camshaft

Coolant recirculates from the radiator to the engine and back to the radiator. Low-temperature coolant leaves the radiator by the bottom outlet. It is pumped into the warm engine block, where it picks up some heat. From the block, the warm coolant flows to the hot cylinder head, where it picks up more heat. NOTE: Some engines use reverse cooling. This means that the coolant flows from the radiator to the cylinder head(s) before flowing to the engine block. Water pumps are not positive displacement pumps. The water pump is a centrifugal pump that can move a large volume of coolant without increasing the pressure of the coolant. The pump pulls coolant in at the center of the impeller. Centrifugal force throws the coolant outward so that it is discharged at the impeller tips. SEE FIGURE 21–17.

FIGURE 21–18 A demonstration engine running on a stand, showing the amount of coolant flow that actually occurs through the cooling system.

?

FREQUENTLY ASKED QUESTION

How Much Coolant Can a Water Pump Move? A typical water pump can move a maximum of about 7,500 gallons (28,000 liters) of coolant per hour, or recirculate the coolant in the engine over 20 times per minute. This means that a water pump could be used to empty a typical private swimming pool in an hour! The slower the engine speed, the less power is consumed by the water pump. However, even at 35 mph (56 km/h), the typical water pump still moves about 2,000 gallons (7,500 liters) per hour or 0.5 gallon (2 liters) per second! SEE FIGURE 21–18.

As engine speeds increase, more heat is produced by the engine and more cooling capacity is required. The pump impeller speed increases as the engine speed increases to provide extra coolant flow at the very time it is needed. Coolant leaving the pump impeller is fed through a scroll. The scroll is a smoothly curved passage that changes the fluid flow

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BEARING ASSEMBLY

SEAL

FIGURE 21–19 This severely corroded water pump could not circulate enough coolant to keep the engine cool. As a result, the engine overheated and blew a head gasket.

FIGURE 21–21 A cutaway of a typical water pump showing the long bearing assembly and the seal. The weep hole is located between the seal and the bearing. If the seal fails, then coolant flows out of the weep hole to prevent the coolant from damaging the bearing.

TECH TIP Release the Belt Tension Before Checking a Water Pump The technician should release water pump belt tension before checking for water pump bearing looseness. To test a water pump bearing, it is normal to check the fan for movement; however, if the drive belt is tight, any looseness in the bearing will not be felt. WEEP HOLE

FIGURE 21–20 The bleed weep hole in the water pump allows coolant to leak out of the pump and not be forced into the bearing. If the bearing failed, more serious damage could result.

direction with minimum loss in velocity. The scroll is connected to the front of the engine so as to direct the coolant into the engine block. On V-type engines, two outlets are often used, one for each cylinder bank. Occasionally, diverters are necessary in the water pump scroll to equalize coolant flow between the cylinder banks of a V-type engine in order to equalize the cooling.

WATER PUMP SERVICE A worn impeller on a water pump can reduce the amount of coolant flow through the engine. SEE FIGURE 21–19. If the seal of the water pump fails, coolant will leak out of the weep hole. The hole allows coolant to escape without getting trapped and forced into the water pump bearing assembly. SEE FIGURE 21–20. The hole allows coolant to escape without getting trapped and forced into the water pump bearing assembly. If the bearing is defective, the pump will usually be noisy and will have to be replaced. Before replacing a water pump that has failed because of a loose or noisy bearing, check all of the following: 1. Drive belt tension 2. Bent fan 3. Fan for balance

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If the water pump drive belt is too tight, excessive force may be exerted against the pump bearing. If the cooling fan is bent or out of balance, the resulting vibration can damage the water pump bearing. SEE FIGURE 21–21.

COOLANT FLOW IN THE ENGINE TYPES OF SYSTEMS

Coolant flows through the engine in one

of the following ways.

Parallel flow system. In the parallel flow system, coolant flows into the block under pressure and then crosses the head gasket to the head through main coolant passages beside each cylinder.

Series flow system. In the series flow system, the coolant flows around all the cylinders on each bank. All the coolant flows to the rear of the block, where large main coolant passages allow the coolant to flow across the head gasket. The coolant then enters the rear of the heads. In the heads, the coolant flows forward to a crossover passage on the intake manifold outlet at the highest point in the engine cooling passage. This is usually located at the front of the engine. The outlet is either on the heads or in the intake manifold.

FAN SHROUD CROSSFLOW RADIATOR

COOLANT PASSAGE

RADIATOR FAN SWITCH GAS VENT

AUTOMATIC TRANSMISSION OIL COOLER FITTINGS

FIGURE 21–22 A Chevrolet V-8 block that shows the large coolant holes and the smaller gas vent or bleed holes that must match the head gasket when the engine is assembled.

Series-parallel flow system. Some engines use a combination of these two coolant flow systems and call it a seriesparallel flow system. Any steam that develops will go directly to the top of the radiator. In series flow systems, bleed holes or steam slits in the gasket, block, and head perform the function of letting out the steam.

COOLANT FLOW AND HEAD GASKET DESIGN

Most V-type engines use cylinder heads that are interchangeable side to side, but not all engines. Therefore, based on the design of the cooling system and flow through the engine, it is very important to double check that the cylinder head is matched to the block and that the head gasket is installed correctly (end for end) so that all of the cooling passages are open to allow the proper flow of coolant through the system. SEE FIGURE 21–22.

COOLING FANS ELECTRONICALLY CONTROLLED COOLING FAN

ELECTRIC FAN BLADES FAN MOTOR

FIGURE 21–23 A typical electric cooling fan assembly showing the radiator and related components. Many rear-wheel-drive vehicles and all transverse engines drive the fan with an electric motor. SEE FIGURE 21–23. NOTE: Most electric cooling fans are computer controlled. To save energy, most cooling fans are turned off whenever the vehicle is traveling faster than 35 mph (55 km/h). The ram air caused by the vehicle speed is enough to keep the radiator cool. Of course, if the computer senses that the temperature is still too high, the computer will turn on the cooling fan, to “high,” if possible, in an attempt to cool the engine to avoid severe engine damage.

WARNING Some electric cooling fans can come on after the engine is off without warning. Always keep hands and fingers away from the cooling fan blades unless the electrical connector has been disconnected to prevent the fan from coming on. Always follow all warnings and cautions.

Two

types of electric cooling fans used on many engines include:

One two-speed cooling fan

Two cooling fans (one for normal cooling and one for high heat conditions)

The PCM commands low-speed fans on under the following conditions.

Engine coolant temperature (ECT) exceeds approximately 223°F (106°C).

A/C refrigerant pressure exceeds 190 PSI (1,310 kPa).

After the vehicle is shut off, the engine coolant temperature at key-off is greater than 284°F (140°C) and system voltage is more than 12 volts. The fan(s) will stay on for approximately three minutes.

The PCM commands the high-speed fan on under the following conditions.

Engine coolant temperature (ECT) reaches 230°F (110°C).

A/C refrigerant pressure exceeds 240 PSI (1,655 kPa).

Certain diagnostic trouble codes (DTCs) set.

To prevent a fan from cycling on and off excessively at idle, the fan may not turn off until the ignition switch is moved to the off position or the vehicle speed exceeds approximately 10 mph (16 km/h).

THERMOSTATIC FANS

On some rear-wheel-drive vehicles, a thermostatic cooling fan is driven by a belt from the crankshaft. It turns faster as the engine turns faster. Generally, the engine is required to produce more power at higher speeds. Therefore, the cooling system will also transfer more heat. Increased fan speed aids in the required cooling. Engine heat also becomes critical at low engine speeds in traffic where the vehicle moves slowly. The thermostatic fan is designed so that it uses little power at high engine speeds and minimizes noise. Two types of thermostatic fans include: 1. Silicone coupling. The silicone coupling fan drive is mounted between the drive pulley and the fan. HINT: When diagnosing an overheating problem, look carefully at the cooling fan. If silicone is leaking, then the fan may not be able to function correctly and should be replaced. 2. Thermostatic spring. A second type of thermal fan has a thermostatic spring added to the silicone coupling fan drive. The thermostatic spring operates a valve that allows the fan to freewheel when the radiator is cold. As the radiator warms to about 150°F (65°C), the air hitting the thermostatic spring will cause the spring to change its shape. The new shape of the

After the engine has been operated, feel the upper radiator hose. If the engine is up to proper operating temperature, the upper radiator hose should be too hot to hold. The hose should also be pressurized. a. If the hose is not hot enough, replace the thermostat. b. If the hose is not pressurized, test or replace the radiator pressure cap if it will not hold the specified pressure. c. If okay, see step 2.

STEP 2

With the engine running, feel both heater hoses. (The heater should be set to the maximum heat position.) Both hoses should be too hot to hold. If both hoses are warm (not hot) or cool, check the heater control valve for proper operation (if equipped). If one hose is hot and the other (return) is just warm or cool, remove both hoses from the heater core or engine and flush the heater core with water from a garden hose.

STEP 3

If both heater hoses are hot and there is still a lack of heating concern, then the fault is most likely due to an airflow blend door malfunction. Check service information for the exact procedure to follow.

Be Sure to Always Use a Fan Shroud A fan shroud forces the fan to draw air through the radiator. If a fan shroud is not used, then air is drawn from around the fan and will reduce the airflow through the radiator. Many overheating problems are a result of not replacing the factory shroud after engine work or body repair work to the front of the vehicle.

spring opens a valve that allows the drive to operate like the silicone coupling drive. When the engine is very cold, the fan may operate at high speeds for a short time until the drive fluid warms slightly. The silicone fluid will then flow into a reservoir to let the fan speed drop to idle. SEE FIGURE 21–24. The fan is designed to move enough air at the lowest fan speed to cool the engine when it is at its highest coolant temperature. The fan shroud is used to increase the cooling system efficiency.

HEATER CORES PURPOSE AND FUNCTION Most of the heat absorbed from the engine by the cooling system is wasted. Some of this heat, however, is recovered by the vehicle heater. Heated coolant is passed through tubes in the small core of the heater. Air is passed across the heater fins and is then sent to the passenger compartment. In some vehicles, the heater and air conditioning work in series to maintain vehicle compartment temperature. SEE FIGURE 21–25.

HINT: Heat from the heater that “comes and goes” is most likely the result of low coolant level. Usually with the engine at idle, there is enough coolant flow through the heater. At higher engine speeds, however, the lack of coolant through the heads and block prevents sufficient flow through the heater.

COOLING SYSTEM TESTING VISUAL INSPECTION

HEATER PROBLEM DIAGNOSIS

When the heater does not produce the desired amount of heat, many owners and technicians replace the thermostat before doing any other troubleshooting. It is true that a defective thermostat is the reason for the engine not to reach normal operating temperature, but there are many other causes besides a defective thermostat that can result in lack of heat from the heater. To determine the exact cause, follow this procedure.

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Many cooling system faults can be found by performing a thorough visual inspection. Items that can be inspected visually include:

Water pump drive belt for tension or faults

Cooling fan for faults

Heater and radiator hoses for condition and leaks

Coolant overflow or surge tank coolant level

PRESSURE TESTER

ADAPTER

FIGURE 21–26 A heavily corroded radiator from a vehicle that was overheating. A visual inspection discovered that the corrosion had eaten away many of the cooling fins, yet did not leak. This radiator was replaced and it solved the overheating problem.

FIGURE 21–27 Pressure testing the cooling system. A typical handoperated pressure tester applies pressure equal to the radiator cap pressure. The pressure should hold; if it drops, this indicates a leak somewhere in the cooling system. An adapter is used to attach the pump to the cap to determine if the radiator can hold pressure, and release it when pressure rises above its maximum rated pressure setting.

Evidence of coolant loss

Radiator condition SEE FIGURE 21–26.

CAP

FIGURE 21–28 The pressure cap should be checked for proper operation using a pressure tester as part of the cooling system diagnosis.

FIGURE 21–29 Use dye specifically made for coolant when checking for leaks using a black light.

3. Radiator 4. Heater core

PRESSURE TESTING Pressure testing using a hand-operated pressure tester is a quick and easy cooling system test. The radiator cap is removed (engine cold!) and the tester is attached in the place of the radiator cap. By operating the plunger on the pump, the entire cooling system is pressurized. SEE FIGURE 21–27. CAUTION: Do not pump up the pressure beyond that specified by the vehicle manufacturer. Most systems should not be pressurized beyond 14 PSI (100 kPa). If a greater pressure is used, it may cause the water pump, radiator, heater core, or hoses to fail. If the cooling system is free from leaks, the pressure should stay and not drop. If the pressure drops, look for evidence of leaks anywhere in the cooling system, including: 1. Heater hoses 2. Radiator hoses

5. Cylinder head 6. Core plugs in the side of the block or cylinder head Pressure testing should be performed whenever there is a leak or suspected leak. The pressure tester can also be used to test the radiator cap. An adapter is used to connect the pressure tester to the radiator cap. Replace any cap that will not hold pressure. SEE FIGURE 21–28.

COOLANT DYE LEAK TESTING

One of the best methods to check for a coolant leak is to use a fluorescent dye in the coolant, one that is specifically designed for coolant. Operate the vehicle with the dye in the coolant until the engine reaches normal operating temperature. Use a black light to inspect all areas of the cooling system. When there is a leak, it will be easy to spot because the dye in the coolant will be seen as bright green. SEE FIGURE 21–29.

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REAL WORLD FIX Highway Overheating

FIGURE 21–30 When an engine overheats, often the coolant overflow container boils.

COOLANT TEMPERATURE WARNING LIGHT PURPOSE AND FUNCTION

Most vehicles are equipped with a heat sensor for the engine operating temperature indicator light. If the warning light comes on during driving (or the temperature gauge goes into the red danger zone), then the coolant temperature is about 250°F to 258°F (120°C to 126°C), which is still below the boiling point of the coolant (assuming a properly operating pressure cap and system). SEE FIGURE 21–30.

Shut off the air conditioning and turn on the heater. The heater will help rid the engine of extra heat. Set the blower speed to high.

STEP 2

If possible, shut the engine off and let it cool. (This may take over an hour.)

STEP 3

Never remove the radiator cap when the engine is hot.

STEP 4

Do not continue to drive with the hot light on, or serious damage to your engine could result.

STEP 5

If the engine does not feel or smell hot, it is possible that the problem is a faulty hot light sensor or gauge. Continue to drive, but to be safe, stop occasionally and check for any evidence of overheating or coolant loss.

A vehicle owner complained of an overheating vehicle, but the problem occurred only while driving at highway speeds. The vehicle, equipped with a 4-cylinder engine, would run in a perfectly normal manner in city driving situations. The technician flushed the cooling system and replaced the radiator cap and the water pump, thinking that restricted coolant flow was the cause of the problem. Further testing revealed coolant spray out of one cylinder when the engine was turned over by the starter with the spark plugs removed. A new head gasket solved the problem. Obviously, the head gasket leak was not great enough to cause any problems until the engine speed and load created enough flow and heat to cause the coolant temperature to soar. The technician also replaced the oxygen (O2) sensor, because the IAT-type coolant contains phosphates and silicates that often contaminate the sensor. The deteriorated oxygen sensor could have contributed to the problem.

The cooling system is one of the most maintenance-free systems in the engine. Normal maintenance involves an occasional check on the coolant level. It should also include a visual inspection for signs of coolant system leaks and for the condition of the coolant hoses and fan drive belts. CAUTION: The coolant level should only be checked when the engine is cool. Removing the pressure cap from a hot engine will release the cooling system pressure while the coolant temperature is above its atmospheric boiling temperature. When the cap is removed, the pressure will instantly drop to atmospheric pressure level, causing the coolant to boil immediately. Vapors from the boiling liquid will blow coolant from the system. Coolant will be lost, and someone may be injured or burned by the high-temperature coolant that is blown out of the filler opening.

ACCESSORY DRIVE BELT TENSION

Drive belt condition and proper installation are important for the proper operation of the cooling system. There are four ways vehicle manufacturers specify that the belt tension is within factory specifications. 1. Belt tension gauge. A belt tension gauge is needed to achieve the specified belt tension. Install the belt and operate the engine with all of the accessories turned on, to run in the belt for at least five minutes. Adjust the tension of the accessory drive belt

torque needed to rotate the tensioner. If the torque reading is below specifications, the tensioner must be replaced. 4. Deflection. Depress the belt between the two pulleys that are the farthest apart and the flex or deflection should be 1/2 in. MARKS ON STATIONARY MOUNT

COOLING SYSTEM SERVICE FLUSHING COOLANT

Flushing the cooling system includes

the following steps. MARKS ON MOVABLE SECTION OF THE TENSIONER

FIGURE 21–31 Typical marks on an accessory drive belt tensioner.

Number of Ribs Used

Tension Range (lb.)

3

45 to 60

4

60 to 80

5

75 to 100

6

90 to 125

7

105 to 145

CHART 21–3 The number of ribs determines the tension range of the belt.

TECH TIP The Water Spray Trick Lower-than-normal alternator output could be the result of a loose or slipping drive belt. All belts (V and serpentine multigroove) use an interference angle between the angle of the Vs of the belt and the angle of the Vs on the pulley. A belt wears this interference angle off the edges of the V of the belt. As a result, the belt may start to slip and make a squealing sound even if tensioned properly. A common trick to determine if the noise is from the belt is to spray water from a squirt bottle at the belt with the engine running. If the noise stops, the belt is the cause of the noise. The water quickly evaporates and therefore, water just finds the problem—it does not provide a short-term fix.

STEP 1

Drain the system (dispose of the old coolant correctly).

STEP 2

Fill the system with clean water and flushing/cleaning chemical.

STEP 3

Start the engine until it reaches operating temperature with the heater on.

Start the engine until it reaches operating temperature with the heater on.

STEP 8

Adjust coolant level as needed.

Bleeding the air out of the cooling system is important because air can prevent proper operation of the heater and can cause the engine to overheat. Use a clear hose attached to the bleeder valve and the other end in a “suitable” container. This prevents coolant from getting on the engine and gives the technician a visual clue as to the color of coolant. SEE FIGURE 21–32. Check service information for specific bleeding procedures and location of the air bleeder fittings.

COOLANT EXCHANGE MACHINE Many coolant exchange machines are able to perform one or more of the following operations.

Exchange old coolant with new coolant

Flush the cooling system

Pressure or vacuum check the cooling system for leaks

The use of a coolant exchange machine pulls a vacuum on the cooling system which helps illuminate air pockets from forming during coolant replacement. If an air pocket were to occur, the following symptoms may occur. 1. Lack of heat from the heater. Air rises and can form in the heater core, which will prevent coolant from flowing. 2. Overheating. The engine can overheat due to the lack of proper coolant flow through the system.

to factory specifications or use CHART 21–3 for an example of the proper tension based on the size of the belt. Replace any serpentine belt that has more than three cracks in any one rib that appears in a 3 in. span. 2. Marks on the tensioner. Many tensioners have marks that indicate the normal operating tension range for the accessory drive belt. Check service information for the location of the tensioner mark. SEE FIGURE 21–31. 3. Torque wrench reading. Some vehicle manufacturers specify that a beam-type torque wrench be used to determine the

Always follow the operating instructions for the coolant exchange machine being used. SEE FIGURE 21–33.

HOSE INSPECTION Coolant system hoses are critical to engine cooling. As the hoses get old, they become either soft or brittle and sometimes swell in diameter. Their condition depends on their material and on the engine service conditions. If a hose breaks while the engine is running, all coolant will be lost. A hose should be replaced any time it appears to be abnormal. SEE FIGURE 21–34.

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CHAFED OR BURNED

BLEEDER VALVE

SOFT AND SPONGY

(a) HARDENED

SWOLLEN OR OIL SOAKED

(b)

FIGURE 21–32 (a) Many vehicle manufacturers recommend that the bleeder valve be opened whenever refilling the cooling system. (b) Chrysler recommends that a clear plastic hose (1/4 in. ID) be attached to the bleeder valve and directed into a suitable container to keep from spilling coolant onto the ground and on the engine and to allow the technician to observe the flow of coolant for any remaining oil bubbles.

FIGURE 21–34 All cooling system hoses should be checked for wear or damage.

TECH TIP Always Replace the Pressure Cap Replace the old radiator cap with a new cap with the same pressure rating. The cap can be located on the following: 1. Radiator 2. Coolant recovery reservoir 3. Upper radiator hose

WARNING Never remove a pressure cap from a hot engine. When the pressure is removed from the system, the coolant will immediately boil and will expand upward, throwing scalding coolant in all directions. Hot coolant can cause serious burns.

HINT: To make hose removal easier and to avoid possible damage to the radiator, use a utility knife and slit the hose lengthwise. Then simply peel the hose off.

FIGURE 21–33 Using a coolant exchange machine helps eliminate the problem of air getting into the system which can cause overheating or lack of heat due to air pockets getting trapped in the system.

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The hose and hose clamp should be positioned so that the clamp is close to the bead on the neck. This is especially important on aluminum hose necks to avoid corrosion. When the hoses are in place and the drain petcock is closed, the cooling system can be refilled with the correct coolant mixture.

TECH TIP Always Use Heater Hoses Designed for Coolant Many heater hoses are sizes that can also be used for other purposes such as oil lines. Always check and use hose that states it is designed for heater or cooling system use. SEE FIGURE 21–35.

TECH TIP Quick and Easy Cooling System Problem Diagnosis 1. If overheating occurs in slow stop-and-go traffic, the usual cause is low airflow through the radiator. Check for airflow blockages or cooling fan malfunction. 2. If overheating occurs at highway speeds, the cause is usually a radiator or coolant circulation problem. Check for a restricted or clogged radiator.

DISPOSING OF USED COOLANT Used coolant drained from vehicles should be disposed of according to state or local laws. Some communities permit draining into the sewer. Ethylene glycol will easily biodegrade. There could be problems with groundwater contamination, however, if coolant is spilled on open ground. Check with recycling companies authorized by local or state governments for the exact method recommended for disposal in your area.

FIGURE 21–35 The top 3/8 in. hose is designed for oil and similar liquids, whereas the 3/8 in. hose below is labeled “heater hose” and is designed for coolant.

CLEANING THE RADIATOR EXTERIOR Overheating can result from exterior and interior radiator plugging. External plugging is caused by dirt and insects. This type of plugging can be seen if you look straight through the radiator while a light is held behind it. It is most likely to occur on off-road vehicles. The plugged exterior of the radiator core can usually be cleaned with water pressure from a hose. The water is aimed at the engine side of the radiator. The water should flow freely through the core at all locations. If this does not clean the core, the radiator should be removed for cleaning at a radiator shop.

REVIEW QUESTIONS 1. What is normal operating coolant temperature?

6. Explain the operation of a thermostatic cooling fan.

2. Explain the flow of coolant through the engine and radiator.

7. Describe how to diagnose a heater problem.

3. Why is a cooling system pressurized?

8. What are 10 common causes of overheating?

4. What is the purpose of the coolant system bypass? 5. Describe how to perform a drain, flush, and refill procedure on a cooling system.

CHAPTER QUIZ 1. The upper radiator collapses when the engine cools. What is the most likely cause? a. Defective upper radiator hose b. Missing spring from the upper radiator hose, which is used to keep it from collapsing c. Defective thermostat d. Defective pressure cap 2. What can be done to prevent air from getting trapped in the cooling system when the coolant is replaced? a. Pour the coolant into the radiator slowly. b. Use a coolant exchange machine that draws a vacuum on the system. c. Open the air bleeder valves while adding coolant. d. Either b or c

3. Heat transfer is improved from the coolant to the air when the ______________. a. Temperature difference is great b. Temperature difference is small c. Coolant is 95% antifreeze d. Both a and c 4. A water pump is a positive displacement type of pump. a. True b. False 5. Water pumps ______________. a. Only work at idle and low speeds and are disengaged at higher speeds b. Use engine oil as a lubricant and coolant c. Are driven by the engine crankshaft or camshaft d. Disengage during freezing weather to prevent radiator failure

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6. What diagnostic trouble code (DTC) could be set if the thermostat is defective? a. P0300 c. P0171 b. P0440 d. P0128 7. Which statement is true about thermostats? a. The temperature marked on the thermostat is the temperature at which the thermostat should be fully open. b. Thermostats often cause overheating. c. The temperature marked on the thermostat is the temperature at which the thermostat should start to open. d. Both a and b 8. Technician A says that the radiator should always be inspected for leaks and proper flow before installing a rebuilt engine. Technician B says that overheating during slow city driving can only be due to a defective electric cooling fan. Which technician is correct? a. Technician A only b. Technician B only c. Both Technicians A and B d. Neither Technician A nor B

chapter

9. A customer complains that the heater works sometimes, but sometimes only cold air comes out while driving. Technician A says that the water pump is defective. Technician B says that the cooling system could be low on coolant. Which technician is correct? a. Technician A only b. Technician B only c. Both Technicians A and B d. Neither Technician A nor B 10. The normal operating temperature (coolant temperature) of an engine equipped with a 195°F thermostat is ______________. a. 175°F to 195°F b. 185°F to 205°F c. 195°F to 215°F d. 175°F to 215°F

INTRODUCTION Engine oil has a major effect on the proper operation and life of any engine. Engine oil provides the following functions in every engine.

Lubricates moving parts

Helps cool engine parts

Helps seal piston rings

Helps to neutralize acids created by the by-products of combustion

Reduces friction in the engine

Helps to prevent rust and corrosion

As a result of these many factors, the specified engine oil must be used and replaced at the specified mileage or time intervals.

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PROPERTIES OF ENGINE OIL The most important engine oil property is its thickness or viscosity.

As oil is cooled, it gets thicker.

As oil is heated, it gets thinner.

Therefore, its viscosity changes with temperature. The oil must not be too thick at low temperatures to allow the engine to start. The lowest temperature at which oil will pour is called its pour point. An index of the change in viscosity between the cold and hot extremes is called the viscosity index (VI). All oils with a high viscosity index thin less with heat than do oils with a low viscosity index. Oils must also be miscible, meaning they are capable of mixing with other oils (brands and viscosities, for example) without causing any problems such as sludge.

SAE RATING TERMINOLOGY Engine oils are sold with a Society of Automotive Engineers (SAE) grade number, which indicates the viscosity range into which the oil fits. Oils tested at 212°F (100°C) have a number with no letter following. For example, SAE 30 indicates that the oil has only been checked at 212°F (100°C). This oil’s viscosity falls within the SAE 30 grade number range when the oil is hot. Oils tested at 0°F (⫺18°C) are rated with a number and the letter W, which means winter and indicates that the viscosity was tested at 0°F, such as SAE 20W. MULTIGRADE ENGINE OIL

SEE FIGURE 22–1. Oil with a high viscosity has a higher resistance to flow and is thicker than lower viscosity oil. Thick oil is not necessarily good oil and thin oil is not necessarily bad oil. Generally, the following items can be considered in the selection of engine oil within the recommended viscosity range.

The American Petroleum Institute (API), working with the engine manufacturers and oil companies, has established an engine oil performance classification. Oils are tested and rated in production automotive engines. The oil container is printed with the API classification of the oil. The API performance or service classification and the SAE grade marking are the only information available to help determine which oil is satisfactory for use in an engine. SEE FIGURE 22–2 for a typical API oil container “doughnut.”

GASOLINE ENGINE RATINGS In gasoline engine ratings, the letter S means service, but can also indicate spark ignition engines. The rating system is open ended so that newer, improved ratings can be readily added as necessary (the letter I is skipped to avoid confusion with the number one). SA

Straight mineral oil (no additives), not suitable for use in any engine

SB

Nondetergent oil with additives to control wear and oil oxidation

SC

Obsolete (1964)

SD

Obsolete (1968)

SE

Obsolete (1972)

SF

Obsolete (1980)

SG

Obsolete (1988)

SH

Obsolete (1993–1997)

SJ

Obsolete (1997–2001)

SL

2001–2003

SM

2004–2010

SN

2011⫹

EN GIN E OIL

199

REAL WORLD FIX The Case of the Wrong Oil Viscosity

•

D

AMERICAN

ER

STITUTE IN

“Oil pressure not reaching specified at 1250 RPM.”

FOR GASOLINE ENGINES

•C

A 2007 Dodge Durango 5.7 liter Hemi with a multiple displacement system (MDS) had the oil changed at a shop. SAE 10W-30 was used as this was the “standard” bulk oil in the shop. After the oil change, the vehicle was returned to the customer. Within a few minutes, however, the “check engine” light came on. The technician checked for diagnostic trouble codes (DTCs) and found a P0521 DTC stored. The technician checked service information and discovered that the code could be set if the incorrect viscosity engine oil had been used. The description of the P0521 read:

TROLEUM PE

TIFIE

FIGURE 22–3 The International Lubricant Standardization and Approval Committee (ILSAC) starburst symbol. If this symbol is on the front of the container of oil, then it is acceptable for use in almost any gasoline engine.

The technician changed the oil and used the specified SAE 5W-20, then cleared the DTC. A test drive confirmed that the change to the correct viscosity oil solved the problem.

TECH TIP Three Oil Change Facts Three facts that are important to know when changing oil are: 1. Recommended SAE viscosity (thickness) for the temperature range that is anticipated before the next oil change (such as SAE 5W-30) 2. Quality rating as recommended by the engine or vehicle manufacturer such as API SM and other specified rating such as the ILSAC and vehicle manufacturer’s specifications 3. Recommended oil change interval (time or mileage) (usually every 5,000 miles or every six months)

NOTE: Vehicles built since about 1996 that use roller valve lifers can use the newer, higher rated engine oil classifications where older, now obsolete ratings were specified. Newly overhauled antique cars or engines also can use the newer, improved oils, as the appropriate SAE viscosity grade is used for the anticipated temperature range. Engines older than an about 1996 or those using flat-bottom lifters should use a zinc additive if using newer rated oil.

DIESEL ENGINE RATINGS

Diesel classifications begin with the letter C, which stands for commercial, but can also indicate compression ignition or diesel engines.

owner and technician know that the oil is suitable for use in almost any gasoline engine. SEE FIGURE 22–3.

CA

Obsolete

CB

Obsolete

CC

Obsolete

The original GF-1 (gasoline fueled) rating in 1993

CD

Minimum rating for use in a diesel engine service

Updated to GF-2 in 1997

CE

Designed for certain turbocharged or supercharged heavy-duty diesel engine service

Required for use in all 2007 and newer diesels using ultra-low-sulfur diesel (ULSD) fuel

ILSAC OIL RATING

EUROPEAN OIL RATING SYSTEM DEFINITION

The Association des Constructeurs Européens d’Automobiles (ACEA) rates the oil according to the following:

DEFINITION

The International Lubricant Standardization and Approval Committee (ILSAC) developed an oil rating that consolidates the SAE viscosity rating and the API quality rating. If an engine oil meets the standards, a “starburst” symbol is displayed on the front of the oil container. If the starburst is present, the vehicle

FIGURE 22–4 ACEA ratings are included on the back of the oil container if it meets any of the standards. ACEA ratings apply to European vehicles only such as BMW, Mercedes, Audi, and VW. ACEA A3

ACEA A4 ACEA A5

Designed for high-performance engines and/or extended oil drain intervals and under all temperature ranges Designed to meet the requirements for gasoline direct injection (GDI) engines Low-viscosity low-friction oil not suitable for some engines

FIGURE 22–5 Viscosity index (VI) improver is a polymer and feels like finely ground foam rubber. When dissolved in the oil, it expands when hot to keep the oil from thinning.

JAPANESE OIL RATINGS The Japanese Automobile Standards Organization (JASO) also publishes oil standards. The JASO tests use small Japanese engines, and their ratings require more stringent valve train wear standards than oil ratings in other countries. However, most Japanese brand vehicles specify SAE, API, and ILSAC rating standards for use in the engine.

Diesel engine oils ACEA B1

ACEA B2

ACEA B3

ACEA B4

ACEA B5 ACEA C1,

Low-viscosity oil designed for use in a passenger vehicle diesel engine that is equipped with an indirect injection system; not suitable for some diesel engines Designed for use in passenger vehicle diesel engines using indirect injection and using normal oil drain intervals Intended for use in a high-performance indirect injected passenger vehicle diesel engine and under extended oil drain interval conditions Intended for year-round use in direct injected passenger vehicle diesel engines; can be used in an indirect injected diesel engine Designed for extended oil drain intervals; not suitable for some engines Specifications for catalyst compatible oils, C2, C3 which have limits on the amount of sulfur, zinc, and other additives that could harm the catalytic converter

Starting in 2004, the ACEA began using combined ratings such as A1/B1, A3/B3, A3/B4, and A5/B5.

ENGINE OIL ADDITIVES Oil producers are careful to check the compatibility of the oil additives they use. A number of chemicals that will help each other can be used for each of the additive requirements. The balanced additives are called an additive package.

ADDITIVES TO IMPROVE THE BASE OIL

Viscosity index (VI) improver. Modifies the viscosity of the base fluid so that it changes less as the temperature rises; allows the lubricant to operate over a wider temperature range ( SEE FIGURE 22–5.)

Pour point depressant. Keeps the lubricant flowing at low temperatures

Antifoam agents. Foam reduces the effectiveness of a lubricant. The antifoam agents reduce/stop foaming when the oil is agitated or aerated.

ADDITIVES TO PROTECT THE BASE OIL

Antioxidants. Slow the breakdown of the base fluid caused by oxygen (air) and heat (Oxidation is the main cause of lubricant degradation in service.)

Oxidants. Prevent acid formation (corrosion) in the form of sludges, varnishes

Total base number (TBN). The reserve alkalinity used to neutralize the acids created during the combustion process (Typical TBN levels are between 60 and 100, which is dependent on the fuel sulfur level. The higher the sulfur percentage in the fuel, the higher the TBN required. The higher the total base

EN GIN E OIL

201

TECH TIP Dirty Engine Oil Can Cause Oil Burning Service technicians have known for a long time that some of their customers never change the engine oil. Often these customers believe that because their engine uses oil and they add a new quart every week, they are doing the same thing as changing the oil. But dirty, oxidized engine oil could cause piston rings to stick and not seal the cylinder. Therefore, when the oil and filter are changed, the clean oil may free the piston rings, especially if the vehicle is driven on a long trip during which the oil is allowed to reach the normal operating temperature. An engine that is mechanically sound, but burning oil, may be “fixed” by simply changing the oil and filter.

number of oil, the longer it can be used in an engine. Long-life oils usually have higher total base numbers than other oils.)

ADDITIVES TO PROTECT THE ENGINE

Rust inhibitor. Inhibits the action of water on ferrous metal such as steel

Corrosion inhibitor. Protects nonferrous metals such as copper

Antiwear additive. Forms a protective layer on metal surfaces to reduce friction and prevent wear when no lubricant film is present

Extreme pressure additive. Functions only when heavy loads and temperatures are occurring

OIL BRAND COMPATIBILITY Many technicians and vehicle owners have their favorite brand of engine oil. The choice is often made as a result of marketing and advertising, as well as comments from friends, relatives, and technicians. If your brand of engine oil is not performing up to your expectations, then you may wish to change brands. For example, some owners experience lower oil pressure with a certain brand than they do with other brands with the same SAE viscosity rating.

Most experts agree that the oil changes are the most important regularly scheduled maintenance for an engine.

It is also wise to check the oil level regularly and add oil when needed.

According to SAE standard J-357, all engine oils must be miscible (compatible) with all other brands of engine oil.

Therefore, any brand of engine oil can be used as long as it meets the viscosity and API standards recommended by the vehicle manufacturer. Even though many people prefer a particular brand, be assured that, according to API and SAE, any major brand name engine oil can be used.

FIGURE 22–6 Using a zinc additive is important when using SM or SN-rated oil in an engine equipped with a flat-bottom lifter, especially during the break-in period.

?

FREQUENTLY ASKED QUESTION

Can Newer Engine Oils Be Used in Engines That Use Flat-Bottom Lifters No. Newer oil standards are designed to reduce phosphates in the engine oil that may leak past piston rings and end up in the exhaust system. These additives found in oil can then damage the catalytic converter. The levels of phosphate and zinc, commonly referred to as zinc dialkyl dithiophosphate (ZDDP or ZDP), have been reduced because they can cause damage to the catalytic converter. Even though engines consume very little oil, if the oil contains zinc, the efficiency of the catalytic converter is reduced. The use of ZDDP was intended to reduce sliding friction in an engine. Sliding friction is usually found in engines that use flat-bottom lifters. Most, if not all, engines produced over the past 15 years have used roller lifters or cam followers, so using the new oil without ZDDP is not a concern. Even diesel oils have reduced amounts of the zinc, so many camshaft manufacturers are recommending the use of an additive. Older oils had up to 0.15% ZDDP and now SM-rated oils list the zinc at just 0.08% or 800 parts per million. • Engine oil had about 1,200 ppm zinc prior to 2001. • In 2001, the zinc was reduced to 1,000 ppm; and in 2005, reduced again to the current 800 ppm. • API ratings do not specify the zinc content, just oil performance. If driving a vehicle with flat-bottom lifters, use engine oil specifically designed for older engines, such as Shell Rotella T, or use an additive, such as General Motor’s engine oil supplement (EOS), part number 1052367 or 88862586, or a zinc additive. Check with camshaft manufacturers for their recommended oil or additive to use. SEE FIGURE 22–6.

SYNTHETIC OIL DEFINITION Synthetic engine oils have been available for years for military, commercial, and general public use. The term synthetic means that it is a manufactured product and not refined from a naturally occurring substance, as engine oil (petroleum base) is

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refined from crude oil. Synthetic oil is processed from several different base stocks using several different methods.

API GROUPS According to the American Petroleum Institute, engine oil is classified into the following groups.

SAE 5W-30 SYNTHETIC OIL

SAE 5W-30 MINERAL (NON-SYNTHETIC) OIL

FIGURE 22–7 Mobil 1 synthetic engine oil is used by several vehicle manufacturers in new engines.

Group I. Mineral, nonsynthetic base oil with few if any additives; suitable for light lubricating needs and rust protection, not for use in an engine

Group II. Mineral oil with quality additive packages; includes most conventional engine oils

Group IV. Synthetic oils made from mineral oil and monomolecular oil called polyalpholefin (POA); includes Mobil 1 ( SEE FIGURE 22–7.)

FIGURE 22–8 Both oils have been cooled to ⫺20°F (⫺29°C). Notice that the synthetic oil on the left flows more freely than the mineral oil on the right even though both are SAE 5W-30. TECH TIP Use Synthetic Engine Oil in Lawn and Garden Equipment Most four-cycle lawn and garden equipment engines are air cooled and operate hotter than many liquid-cooled engines. Lawn mowers and other small engines are often operated near or at maximum speed and power output for hours at a time. These operating conditions are hard on any engine oil. Try using synthetic oil. The cost is not as big a factor because most small four-cycle lawn mower engines require only about 1/2 quart (1/2 liter) of oil. The synthetic oil is able to perform under high temperatures better than conventional mineral oils.

Group V. Nonmineral sources such as alcohol from corn called diesters or polyolesters; includes Red Line synthetic oil

Groups III, IV, and V are considered to be synthetic because the molecular structure of the finished product does not occur naturally, but is man-made through chemical processes. All synthetic engine oils perform better than group II (mineral) oils, especially when tested according to the Noack Volatility Test ASTM D-5800. This test procedure measures the ability of an oil to stay in grade after it has been heated to 300°F (150°C) for one hour. The oil is then measured for percentage of weight loss. As the lighter components boil off, the oil’s viscosity will increase.

ADVANTAGES OF SYNTHETICS

The major advantage of using synthetic engine oil is its ability to remain fluid at very low temperatures. SEE FIGURE 22–8. This characteristic of synthetic oil makes it popular in colder climates where cold-engine cranking is important.

VEHICLE MANUFACTURER–SPECIFIC OIL SPECIFICATIONS The oil used should meet the specifications of the vehicle manufacturer, which include the following:

BMW Longlife-98 and longlife-01 (abbreviated LL-01), LL-04

General Motors GM 6094M

DISADVANTAGES OF SYNTHETICS

The major disadvantage is cost. The cost of synthetic engine oils can be four to five times the cost of petroleum-based engine oils.

Some oils can meet industry specifications, such as SAE, API, and/or ILSAC ratings, but not pass the tests specified by the vehicle manufacturer.

Honda/Acura HTO-06 (turbocharged engine only)

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OIL DRAIN-BACK VALVE

FIGURE 22–9 European vehicle manufacturers usually specify engine oil with a broad viscosity range, such as SAE 5W-40, and their own unique standards, such as the Mercedes specification 229.51. Always use the oil specified by the vehicle manufacturer.

502.00, 505.00, 505.01, 503, 503.01, 505, 506 diesel, 506.1 diesel, and 507 diesel Be sure to use the oil that meets all of the specifications, especially during the warranty period. NOTE: Most Asian brand vehicle manufacturers do not specify any specifications other than SAE, API, and ILSAC. These vehicles include:

Acura/Honda

Toyota/Lexus/Scion

Kia

Hyundai

Nissan/Infinity

Mitsubishi

Mazda

Suzuki

HIGH MILEAGE OILS DEFINITION A “high mileage oil” is sold for use in vehicles that have over 75,000 miles and are, therefore, nearing the eight-year, 80,000-mile catalytic converter warranty period. Usually higher viscosity and lack of friction-reducing additives mean that most high mileage oils cannot meet ILSAC GF-4 rating and are, therefore, not recommended for use in most engines. DIFFERENCES

Esters are added to swell oil seals (main and valve-stem seals).

The oil is used only in engines with higher than 75,000 miles.

The oil usually does not have the energy rating of conventional oils (i.e., will not meet the specifications for use according to the owner manual in most cases).

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FIGURE 22–10 A rubber diaphragm acts as an antidrainback valve to keep the oil in the filter when the engine is stopped and the oil pressure drops to zero.

OIL FILTERS CONSTRUCTION The oil within the engine is pumped from the oil pan through the filter before it goes into the engine lubricating system passages. The filter is made from either closely packed cloth fibers or a porous paper. Large particles are trapped by the filter. Microscopic particles will flow through the filter pores. These particles are so small that they can flow through the bearing oil film and not touch the surfaces, so they do no damage. OIL FILTER VALVES Many oil filters are equipped with an antidrainback valve that prevents oil from draining out of the filter when the engine is shut off. SEE FIGURE 22–10. This valve keeps oil in the filter and allows the engine to receive immediate lubrication as soon as the engine starts. Either the engine or the filter is provided with a bypass valve that will allow the oil to go around the filter element. SEE FIGURE 22–11. The bypass allows the engine to be lubricated with dirty oil, rather than having no lubrication, if the filter becomes plugged. The oil also goes through the bypass when the oil is cold and thick. OIL FILTER DISPOSAL

Oil filters should be crushed and/ or drained of oil before discarding. After the oil has been drained, the filter can usually be disposed of as regular metal scrap. Always check and follow local, state, or regional oil filter disposal rules, regulations, and procedures. SEE FIGURE 22–12.

OIL CHANGE INTERVALS

All vehicle and engine manufacturers recommend a maximum oil change interval. The recommended intervals are almost always expressed in terms of mileage or elapsed time (or hours of operation), whichever milestone is reached first. Most vehicle manufacturers recommend an oil change interval of 7,500 to 12,000 miles (12,000 to 19,000 km) or every six months. If,

?

FREQUENTLY ASKED QUESTION

Why Change Oil If the Oil Filter Can Trap All the Dirt? Many persons believe that oil filters will remove all dirt from the oil being circulated through the filtering material. Most oil filters will filter particles that are about 10 to 20 microns in size. A micron is one-millionth of a meter or 0.000039 in. Most dirt and carbon particles that turn engine oil black are less than a micron in size. In other words, it takes about 3 million of these carbon particles to cover a pin head. To help visualize the smallness of a micron, consider that a typical human hair is 60 microns in diameter. In fact, anything smaller than 40 microns is not visible to the human eye. The dispersants added to engine oil prevent dirt from adhering together to form sludge. It is the same dispersant additive that prevents dirt from being filtered or removed by other means. If an oil filter could filter particles down to 1 micron, it would be so restrictive that the engine would not receive sufficient oil through the filter for lubrication. Oil recycling companies use special chemicals to break down the dispersants, which permit the dirt in the oil to combine into larger units that can be filtered or processed out of the oil.

FIGURE 22–11 A cutaway of a typical spin-on oil filter. Engine oil enters the filter through the small holes around the center of the filter and flows through the pleated paper filtering media and out the large hole in the center of the filter. The center metal cylinder with holes is designed to keep the paper filter from collapsing under the pressure. The bypass valve can be built into the center on the oil filter or is part of the oil filter housing and located in the engine.

OIL LIFE MONITORS Most vehicles built since the mid-1990s are equipped with a warning light that lets the driver know when the engine oil should be changed. The two basic types of oil change monitoring systems include:

FIGURE 22–12 A typical filter crusher. The hydraulic ram forces out most of the oil from the filter. The oil is trapped underneath the crusher and is recycled. however, any one of the conditions in the following list exists, the oil change interval recommendation drops to a more reasonable 2,000 to 3,000 miles (3,000 to 5,000 km) or every three months. The important thing to remember is that these are recommended maximum intervals and they should be shortened substantially if any of the following operating conditions exist.

Mileage only. The service light will come on based on mileage only and may include a service “A” or “B” based on what service needs to be performed. The interval can be every 3,750 to 7,500 miles, or even longer in some cases where specialized engine oil is required.

Algorithm. Computer programs contain algorithms that specify instructions a computer should perform (in a specific order) to carry out a task. This program uses the number of cold starts, the run time of the engine, and inputs from the engine coolant temperature (ECT) sensor to determine when the oil should be changed.

SEE FIGURE 22–13.

OIL CHANGE PROCEDURE STEP 1

Check the oil level on the dipstick before hoisting the vehicle. Document the work order and notify the owner if the oil level is low before changing the oil.

STEP 2

Safely hoist the vehicle.

STEP 3

Position a drain pan under the drain plug, then remove the plug with care to avoid contact with hot oil.

1. Operating in dusty areas 2. Towing a trailer

CAUTION: Used engine oil has been determined to be harmful. Rubber gloves should be worn to protect the skin. If used engine oil gets on the skin, wash thoroughly with soap and water.

3. Short-trip driving, especially during cold weather (The definition of a short trip varies among manufacturers, but it is usually defined as 4 to 15 miles (6 to 24 km) each time the engine is started.) 4. Operating in temperatures below freezing (32°F, 0°C)

STEP 4

Allow the oil to drain freely so that the contaminants come out with the oil. It is not critically important to get every last drop of oil from the engine oil pan, because a quantity of used oil still remains in the engine oil passages and oil pump.

STEP 5

While the engine oil is draining, the oil plug gasket should be examined. If it appears to be damaged, it should be replaced.

5. Operating at idle speed for extended periods of time (such as normally occurs in police or taxi service) Because most vehicles driven during cold weather are driven on short trips, technicians and automotive experts recommend changing the oil every 2,000 to 3,000 miles or every two to three months, whichever occurs first.

An oil change includes the following

steps.

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FIGURE 22–13 Many vehicle manufacturers can display the percentage of oil life remaining, whereas others simply turn on a warning lamp when it has been determined that an oil change is required.

(a)

TECH TIP Follow the Seasons Vehicle owners often forget when they last changed the oil. This is particularly true of the person who owns or is responsible for several vehicles. A helpful method for remembering when the oil should be changed is to change it at the start of each season of the year. • • • •

Remembering that the oil needs to be changed on these dates helps owners budget for the expense and the time needed.

(b)

FIGURE 22–14 (a) A pick is pushed through the top of an oil filter that is positioned vertically. (b) When the pick is removed, a small hole allows air to get into the top of the filter which then allows the oil to drain out of the filter and back into the engine. TECH TIP

TECH TIP Change Oil Every Friday? The Pick Trick Removing an oil filter that is installed upside down can be a real mess. When this design filter is loosened, oil flows out from around the sealing gasket. To prevent this from happening, use a pick to poke a hole in the top of the filter, as shown in FIGURE 22–14. This small hole allows air to get into the filter, thereby allowing the oil to drain back into the engine rather than remain in the filter. After punching a hole in the filter, be sure to wait several minutes to allow time for the trapped oil to drain down into the engine before loosening the filter.

NOTE: Honda/Acura recommends that the oil drain plug gasket be replaced at every oil change on many of their vehicles. The aluminum sealing gasket does not seal once it has been tightened. Always follow the vehicle manufacturer’s recommendations. STEP 6

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When the oil stops running and starts to drip, reinstall and tighten the drain plug. Replace the oil filter.

CHAPTER 2 2

A vehicle less than one year old came back to the dealer for some repair work. While writing the repair order, the service advisor noted that the vehicle had 88,000 miles on the odometer and was, therefore, out of warranty for the repair. Because the owner approved the repair anyway, the service advisor asked how he had accumulated so many miles in such a short time. The owner said that he was a traveling salesperson with a territory of “east of the Mississippi River.” Because the vehicle looked to be in new condition, the technician asked the salesperson how often he had the oil changed. The salesperson smiled and said proudly, “Every Friday.” Many fleet vehicles put on over 2,000 miles per week. How about changing their oil based on the time since last changed instead of by mileage?

STEP 7

Refill the engine with the proper type, grade, and quantity of oil. Restart the engine and allow the engine to idle until it develops oil pressure; then check the engine for leaks, especially at the oil filter.

OIL CHANGE

1

Before entering the customer’s car for the first time, be sure to install a seat cover as well as a steering wheel cover to protect the vehicle’s interior.

2

Run the engine until it is close to operating temperature. This will help the used oil drain more quickly and thoroughly.

3

Raise the vehicle on a hoist, and place the oil drain container in position under the oil drain plug. Be sure to wear protective gloves.

4

Remove the plug and allow the hot oil to drain from the engine. Use caution during this step as hot oil can cause painful burns!

5

While the engine oil continues to drain, remove the engine oil filter using a filter wrench. Some oil will drain from the filter, so be sure to have the oil drain container underneath when removing it.

6

Compare the new oil filter with the old one to be sure that it is the correct replacement.

CONTINUED

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OIL CHANGE

(CONTINUED)

7

The wise service technician adds oil to the oil filter whenever possible. This provides faster filling of the filter during start-up and a reduced amount of time that the engine does not have oil pressure.

9

Clean the area where the oil filter gasket seats to be sure that no part of the gasket remains that could cause an oil leak if not fully removed.

11 208

Carefully inspect the oil drain plug and gasket. Replace the gasket as needed. Install the drain plug and tighten firmly but do not overtighten!

CHAPTER 2 2

8

Apply a thin layer of clean engine oil to the gasket of the new filter. This oil film will allow the rubber gasket to slide and compress as the oil filter is being tightened.

10

Install the new oil filter and tighten it by hand. Do not use an oil filter wrench to tighten the filter! Most filters should be tightened 3/4 of a turn after the gasket contacts the engine.

12

Lower the vehicle and clean around the oil fill cap before removing it.

STEP BY STEP

13

15

17

Use a funnel to add the specified amount of oil to the engine at the oil fill opening. When finished, replace the oil fill cap.

Stop the engine and let it sit for a few minutes to allow the oil to drain back into the oil pan. Look underneath the vehicle to check for any oil leaks at the oil drain plug(s) or oil filter.

Reinstall the oil-level dipstick. Remove the dipstick a second time and read the oil level.

14

Start the engine and allow it to idle while watching the oil pressure gauge and/or oil pressure warning lamp. Oil pressure should be indicated within 15 seconds of starting the engine.

16

Remove the oil-level dipstick and wipe it clean with a shop cloth.

18

The oil level should be between the MIN and the MAX lines. In this case, the oil level should be somewhere in the cross-hatched area of the dipstick.

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REVIEW QUESTIONS 1. What property of oil does the SAE ratings reflect?

3. Why is the oil filter bypassed when the engine oil is cold and thick?

2. List the vehicle manufacturer’s oil specifications.

4. What are the steps in performing an oil change?

CHAPTER QUIZ 1. The “W” in SAE 5W-20 means ______________. a. Weight c. With b. Winter d. Without 2. Oil change intervals as specified by the vehicle manufacturer ______________. a. Are maximum time and mileage intervals b. Are minimum time and mileage intervals c. Only include miles driven between oil changes d. Generally only include time between oil changes 3. Most conventional (mineral) oil is made from what API group? a. Group I c. Group III b. Group II d. Group IV or V 4. Which rating is the ACEA rating specified for use by many European vehicle manufacturers? a. SAE c. SM b. A3/B3 d. GF-4 5. Technician A says that the engine oil used should meet the vehicle manufacturer’s standards. Technician B says that the specified viscosity of oil be used. Which technician is correct? a. Technician A only b. Technician B only c. Both Technicians A and B d. Neither Technician A nor B 6. Technician A says that some vehicle manufacturers recommend an ILSAC grade be used in the engine. Technician B says that an oil with the specified API rating and SAE viscosity rating should be used in an engine. Which technician is correct? a. Technician A only b. Technician B only c. Both Technicians A and B d. Neither Technician A nor B

chapter

23

7. Two technicians are discussing oil filters. Technician A says that the oil will remain perfectly clean if just the oil filter is changed regularly. Technician B says that oil filters can filter particles smaller than the human eye can see. Which technician is correct? a. Technician A only b. Technician B only c. Both Technicians A and B d. Neither Technician A nor B 8. The purpose of the oil filter bypass valve is to ______________. a. Allow oil to bypass the filter if the filter becomes clogged b. Keep the oil from draining out of the filter when the engine is off and the oil pressure drops to zero c. Allows oil to bypass the oil filter when the oil is hot, to help cool the oil d. Both a and b 9. Different brands of oil can be used in a vehicle from one oil change to another if they meet the vehicle specifications, because all oil is ______________. a. The same API group b. Miscible c. Of the same viscosity d. Both a and c 10. Older engines that use flat-bottom lifers should use oil (or an additive) that has enough ______________. a. Viscosity b. ZDDP (zinc) c. Polyalpholefin (POA) d. Diesters

INTRODUCTION Engine oil is the lifeblood of any engine. The purposes of a lubrication system include the following: 1. Lubricating all moving parts to prevent wear 2. Helping to cool the engine 3. Helping to seal piston rings 4. Cleaning, and holding dirt in suspension in the oil until it can be drained from the engine 5. Neutralizing acids that are formed as the result of the combustion process 6. Reducing friction 7. Preventing rust and corrosion

LUBRICATION PRINCIPLES PURPOSE AND FUNCTION Lubrication between two moving surfaces results from an oil film that separates the surfaces and supports the load. SEE FIGURE 23–1. Although oil does not compress, it does leak out around the oil clearance between the shaft and the bearing. In some cases, the oil film is thick enough to keep the surfaces from seizing, but can allow some contact to occur. This condition is called boundary lubrication. The specified oil viscosity and oil clearances must be adhered to during service to help prevent boundary lubrication and wear from occurring, which usually happens when the engine is under a heavy load and low speeds. The movement of the shaft helps prevent contact with the bearing. If oil were put on a flat surface and a heavy block were pushed across the surface, the block would slide more easily than if it were pushed across a dry surface. The reason for this is that a wedge-shaped oil film is built up between the moving block and the surface, as illustrated in FIGURE 23–2.

FIGURE 23–3 Wedge-shaped oil film curved around a bearing journal.

HYDRODYNAMIC LUBRICATION This wedging action is called hydrodynamic lubrication, and depends on the force applied to the rate of speed between the objects and the thickness of the oil. Thickness of oil is called the viscosity, and is defined as the ability of the oil to resist flow. High-viscosity oil is thick and low-viscosity oil is thin.

The prefix hydro- refers to liquids, as in hydraulics.

The term dynamic refers to moving materials.

Hydrodynamic lubrication occurs when a wedge-shaped film of lubricating oil develops between two surfaces that have relative motion between them. SEE FIGURE 23–3. The engine oil pressure system feeds a continuous supply of oil into the lightly loaded part of the bearing oil clearance. Hydrodynamic lubrication takes over as the shaft rotates in the bearing to produce a wedge-shaped hydrodynamic oil film that is curved around the bearing. The pressure between the bearings and the crankshaft can exceed 1,000 PSI (6,900 kPa) due to hydrodynamic lubrication, as created by the wedging action between the bearing and the crankshaft journal. Most bearing wear occurs during the initial start-up, and continues until a hydrodynamic film is established.

ENGINE LUBRICATION SYSTEMS PURPOSE AND FUNCTION

The primary function of the engine lubrication system is to maintain a positive and continuous oil supply to the bearings. Engine oil pressure must be high enough to get the oil to the bearings with enough force to cause the oil flow that is required for proper cooling.

NORMAL OIL PRESSURE The normal engine oil pressure range is from 10 to 60 PSI (200 to 400 kPa) or 10 PSI per 1000 engine RPM. It is normal to see the following:

Higher oil pressure when the engine is cold due to the oil being cold and at a higher viscosity

Lower oil pressure when the engine is at normal operating temperature due to the oil becoming thinner even though it is multiviscosity oil

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CAMSHAFT DISTRIBUTOR SHAFT

DRIVE GEAR FOR DISTRIBUTOR AND OIL PUMP

OIL PUMP

FIGURE 23–4 The dash oil pressure gauge may be a good indicator of engine oil pressure. If there is any concern about the oil pressure, always use a mechanical gauge to be sure.

The relatively low engine oil pressures obviously could not support these high bearing loads without hydrodynamic lubrication. Oil pressure measurements only show the oil pump pressure and not the pressure created between the bearings and the crankshaft journal due to hydrodynamic forces. SEE FIGURE 23–4.

OIL TEMPERATURE

Excessive temperatures, either too low or too high, are harmful to any engine. If the oil is too cold, it could be too thick to flow through the oil passages and lubricate all engine parts. If the oil is too hot, it could become too thin to provide the film strength necessary to prevent metal-to-metal contact and wear. Estimated oil temperature can be determined with the following formula. Estimated oil temperature ⴝ Outside air temperature ⴙ 120°F For example, 90°F outside air temperature ⫹ 120°F ⫽ 210°F estimated oil temperature. During hard acceleration (or high-power demand activities such as trailer towing), the oil temperature will quickly increase. Oil temperature should not exceed 300°F (150°C).

OIL PUMPS

PUMP BODY

OUTLET

FIGURE 23–6 In an external gear-type oil pump, the oil flows through the pump around the outside of each gear. This is an example of a positive displacement pump, wherein everything entering the pump must leave the pump.

The oil pump is driven from the end of the distributor shaft, often with a hexagon-shaped shaft. Some engines have a short shaft with a gear that meshes with the cam gear to drive both the distributor and oil pump. With a distributor-driven oil pump, the pump turns at one-half engine speed. On crankshaft-driven oil pump systems, the oil pump assembly is often made as part of the engine’s front cover so that it turns at the same speed as the crankshaft.

TYPES OF OIL PUMPS

All oil pumps are called positive displacement pumps, and each rotation of the pump delivers the same volume of oil; therefore, everything that enters must exit. Also a positive displacement pump will deliver more oil and higher pressure as the speed of the pump increases. Most automotive engines use one of two types of oil pumps, either gear or rotor.

PURPOSE AND FUNCTION

All production automobile engines have a full-pressure oil system. The oil pump is required to:

Provide 3 to 6 gallons per minute of engine oil to lubricate the engine

Maintain pressure, by forcing the oil into the lubrication system under pressure

PARTS AND OPERATION

In most engines that use a distributor, the distributor drive gear meshes with a gear on the camshaft, as shown in FIGURE 23–5.

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External gear type. A gear-type oil pump is usually driven by a shaft from the distributor, which is driven by the camshaft. As a result, this type of pump rotates at half engine (crankshaft) speed. The gear-type oil pump consists of two spur gears in a close-fit housing—one gear is driven while the other idles. As the gear teeth come out of mesh, they tend to leave a space, which is filled by oil drawn through the pump inlet. When the pump is pumping, oil is carried around the outside of each gear in the space between the gear teeth and the housing. As the teeth mesh in the center, oil is forced from the teeth into an oil passage, thus producing oil pressure. SEE FIGURE 23–6.

FIGURE 23–9 Gerotor-type oil pump driven by the crankshaft.

CALIBRATED SPRING

EXCESS PRESSURE

PISTON

FIGURE 23–7 A typical internal/external oil pump mounted in the front cover of the engine that is driven by the crankshaft.

A. OIL IS PICKED UP IN LOBE OF OUTER ROTOR. B. OIL IS MOVED IN LOBE OF OUTER ROTOR TO OUTLET. C. OIL IS FORCED OUT OF OUTLET BECAUSE THE INNER AND OUTER ROTORS MESH TOO TIGHTLY AT POINT 1 AND THE OIL CANNOT PASS THROUGH.

FIGURE 23–8 The operation of a rotor-type oil pump.

Internal/external gear type. This type of oil pump is driven by the crankshaft and operates at engine speed. In this style of oil pump, two gears and a crescent stationary element are used. SEE FIGURE 23–7.

Rotor type. This rotor-type oil pump is driven by the crankshaft and uses a special lobe-shape gear meshing with the inside of a lobed rotor. The center lobed section is driven and the outer section idles. As the lobes separate, oil is drawn in just as it is drawn into gear-type pumps. As the pump rotates, it carries oil around and between the lobes. As the lobes mesh, they force the oil out from between them under pressure in the same manner as the gear-type pump. The pump is sized so that it will maintain a pressure of at least 10 PSI (70 kPa) in the oil gallery when the engine is hot and idling. Pressure will increase because the engine-driven pump also rotates faster. SEE FIGURE 23–8.

Gerotor type. This type of positive displacement oil pump uses an inner and an outer rotor. The term is derived from two words: “generated rotor,” or gerotor. The inner rotor has one fewer teeth than the outer rotor and both rotate. SEE FIGURE 23–9.

OIL PRESSURE REGULATION

In engines with a full-pressure lubricating system, maximum pressure is limited with a pressure

relief valve. The relief valve (sometimes called the pressure regulating valve) is located at the outlet of the pump. The relief valve controls maximum pressure by bleeding off oil to the inlet side of the pump. SEE FIGURE 23–10. The relief valve spring tension determines the maximum oil pressure. If a pressure relief valve is not used, the engine oil pressure will continue to increase as the engine speed increases. Maximum pressure is usually limited to the lowest pressure that will deliver enough lubricating oil to all engine parts that need to be lubricated. The oil pump is made so that it is large enough to provide pressure at low engine speeds and small enough that it will not cavitate at high speed. Cavitation occurs when the pump tries to pull oil faster than it can flow from the pan to the pickup. When it cannot get enough oil, it will pull air. This puts air pockets or cavities in the oil stream. A pump is cavitating when it is pulling air or vapors. NOTE: The reason for sheet metal covers over the pickup screen is to prevent cavitation. Oil is trapped under the cover, which helps prevent the oil pump from drawing in air, especially during sudden stops or during rapid acceleration. After the oil leaves the pump, it first flows through the oil filter and then is delivered to the moving parts through drilled oil passages. SEE FIGURE 23–11.

FACTORS AFFECTING OIL PRESSURE

Oil pressure can only be produced when the oil pump has a capacity larger than all the “leaks” in the engine.

Leaks. The leaks are the clearances at end points of the lubrication system. The end points are at the edges of bearings, the rocker arms, the connecting rod spit holes, and so on. These clearances are designed into the engine and are necessary for its proper operation. As the engine parts wear

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HYDRAULIC VALVE LIFTER (CAM FOLLOWER) OIL OIL RETURNS GALLERIES

OVERHEAD CAMSHAFT

PRESSURE OILING TO CRANKSHAFT, CAMSHAFT, AND ROCKER ARMS

SPLASH OILING AND RETURN TO SUMP

CAMSHAFT

FILTER BYPASS VALVE

SPLASH OILING TO CYLINDER WALLS

OIL FILTER

OIL PUMP CRANKSHAFT = GRAVITY RETURN = PRESSURE

FILTER FEED GALLERY

CRANKSHAFT

PICKUP TUBE AND SCREEN

END VIEW

SIDE VIEW

FIGURE 23–11 A typical engine design that uses both pressure and splash lubrication. Oil travels under pressure through the galleries (passages) to reach the top of the engine. Other parts are lubricated as the oil flows back down into the oil pan or is splashed onto parts.

?

FREQUENTLY ASKED QUESTION

Is a High-Pressure or High-Volume Oil Pump Needed? No. Engine parts need pressure after the oil reaches the parts that are to be lubricated. The oil film between the parts is developed and maintained by hydrodynamic lubrication. Excessive oil pressure requires more horsepower and provides no better lubrication than the minimum effective pressure. A high-volume pump is physically larger and pumps more oil with each revolution. A high-volume pump is used mostly in race engines where the main and rod bearing clearances are much greater than normal and therefore would need a great volume of oil to make up for the oil leaking from the wide clearances.

Viscosity of the engine oil. The viscosity of the oil affects both the pump capacity and the oil leakage. Thin oil or oil of very low viscosity slips past the edges of the pump and flows freely from the leaks. Hot oil has a low viscosity, and therefore, a hot engine often has low oil pressure. Cold oil is more viscous (thicker) than hot oil. This results in higher pressures, even with the cold engine idling. High oil pressure occurs with a cold engine, because the oil relief valve must open farther to release excess oil than is necessary with a hot engine. This larger opening increases the spring compression force, which in turn increases the oil pressure. Putting higher viscosity oil in an engine will raise the engine oil pressure to the regulated setting of the relief valve at a lower engine speed.

OIL PUMP CHECKS

The cover is removed to check the condi-

tion of the oil pump.

and clearance becomes greater, more oil will leak out. In other words, worn main or rod bearings are often the cause of lower than normal oil pressure.

Oil pump capacity. The oil pump must supply extra oil for any leaks. The capacity of the oil pump results from its size, rotating speed, and physical condition. When the pump is rotating slowly as the engine idles, oil pump capacity is low. If the leaks are greater than the pump capacity, engine oil pressure is low. As the engine speed increases, the pump capacity increases and the pump tries to force more oil out of the leaks. This causes the pressure to rise until it reaches the regulated maximum pressure. NOTE: A clogged oil pump pickup screen can cause lower than normal oil pressure because the amount of oil delivered by the pump is reduced by the clogged screen.

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Visual inspection. The gears and housing are examined for scoring. If the gears and housing are heavily scored, the entire pump should be replaced. SEE FIGURE 23–12.

Measurements. If they are lightly scored, the clearances in the pump should be measured. These clearances include the space between the gears and housing, the space between the teeth of the two gears, and the space between the side of the gear and the pump cover. A feeler gauge is often used to make these measurements. Gauging plastic can be used to measure the space between the side of the gears and the cover. The oil pump should be replaced when excessive clearance or scoring is found.

On most engines, the oil pump should be replaced as part of any engine work, especially if the cause for the repair is lack of lubrication. NOTE: The oil pump is the “garbage pit” of the entire engine. Any and all debris is often forced through the gears and housing of an oil pump. SEE FIGURE 23–13.

(a)

(a)

(b)

FIGURE 23–12 (a) A visual inspection indicated that this pump cover was worn. (b) An embedded particle of something was found on one of the gears, making this pump worthless except for scrap metal.

FIGURE 23–13 (a) The oil pump is the only part in an engine that gets unfiltered engine oil. The oil is drawn up from the bottom of the oil pan and is pressurized before flowing to the oil filter. (b) If debris gets into an oil pump, the drive or distributor shaft can twist and/or break. When this occurs, the engine will lose all oil pressure.

OIL PASSAGES

3. Rotor tip clearance: 0.010 in. (0.25 mm) 4. Gear end play clearance: 0.004 in. (0.10 mm) All parts should also be inspected closely for wear. Check the relief valve for scoring and check the condition of the spring. When installing the oil pump, coat the sealing surfaces with engine assembly lubricant. This lubricant helps draw oil from the oil pan on initial start-up.

PURPOSE AND FUNCTION

Oil from the oil pump first flows through the oil filter then goes through a drilled hole that intersects with a drilled main oil gallery, or longitudinal header. This is a long hole drilled from the front of the block to the back.

Inline engines use one oil gallery.

V-type engines may use two or three galleries.

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Passages drilled through the block bulkheads allow the oil to go from the main oil gallery to the main and cam bearings. SEE FIGURE 23–14. In some engines, oil goes to the cam bearings first, and then to the main bearings. It is important that the oil holes in the bearings match with the drilled passages in the bearing saddles so that the TECH TIP The New Hemi Engine Oiling System

bearing can be properly lubricated. Over a long period of use, bearings will wear. This wear causes excess clearance. The excess clearance will allow too much oil to leak from the side of the bearing. When this happens, there will be little or no oil left for bearings located farther downstream in the lubricating system. This is a major cause of bearing failure. To aid in bearing failure diagnosis, on most engines, the last rod bearing to receive oil pressure is typically the bearing farthest from the oil pump. If this bearing fails, then suspect low oil pressure as the probable cause.

VALVE TRAIN LUBRICATION

The oil gallery may intersect or have drilled passages to the valve lifter bores to lubricate the lifters. When hydraulic lifters are used, the oil pressure in the gallery keeps refilling them. On some engines, oil from the lifters goes up the center of a hollow pushrod to lubricate the pushrod ends, the rocker arm pivot, and the valve stem tip. In other engines, an oil passage is drilled from either the gallery or a cam bearing to the block deck, where it matches with a head gasket hole and a hole drilled in the head to carry the oil to a rocker arm shaft. Some engines use an enlarged bolt hole to carry lubrication oil around the rocker shaft cap screw to the rocker arm shaft.

The Chrysler Hemi V-8 engine uses a unique oiling system because the valve lifters are fed oil from the top of the cylinder heads and through the pushrods. While it is normal to have oil flowing through hollow pushrods, it is unique that in the Hemi V-8 the oil flows backward from normal and from the head down the hollow pushrods to the lifters. Be sure to use the specified viscosity of oil, as this is critical for proper lubrication of the valve lifters.

BEARING CAP CAVITY

JET HOLE CAMSHAFT LUBRICATION

CYLINDER AND OIL GALLERY CYLINDER HEAD OIL GALLERY

CAMSHAFT JOURNAL SLOT

HYDRAULIC LIFTERS

TURBOCHARGER LUBRICATION (IF EQUIPPED)

RESTRICTOR

MAIN GALLERY

BALANCE SHAFT GALLERY

OIL PUMP INTERMEDIATE SHAFT

FIGURE 23–14 An intermediate shaft drives the oil pump on this overhead camshaft engine. Note the main gallery and other drilled passages in the block and cylinder head.

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OIL DRAINBACK HOLES

FIGURE 23–15 Oil is sent to the rocker arms on this Chevrolet V-8 engine through the hollow pushrods. The oil returns to the oil pan through the oil drainback holes in the cylinder head. Holes in the bottom of the rocker arm shaft allow lubrication of the rocker arm pivot. Rocker arm assemblies need only a surface coating of oil, so the oil flow to the rocker assembly is minimized using restrictions or metered openings. The restriction or metering disk is in the lifter when the rocker assembly is lubricated through the pushrod. Oil that seeps from the rocker assemblies is returned to the oil pan through drain holes. These oil drain holes are often placed so that the oil drains on the camshaft or cam drive gears to lubricate them. Oil drain holes can be either machined or cast into the cylinder heads and block. SEE FIGURE 23–15. Some engines have means of directing a positive oil flow to the cam drive gears or chain. This may include either of the following:

Nozzle

Chamfer on a bearing parting surface, which allows oil to spray on the loaded portion of the cam drive mechanism

OIL PANS

BUILT-IN WINDAGE TRAY

FIGURE 23–16 A typical oil pan with a built-in windage tray used to keep oil from being churned up by the rotating crankshaft.

?

FREQUENTLY ASKED QUESTION

Why Is It Called a Windage Tray? A windage tray is a plate or baffle installed under the crankshaft and is used to help prevent aeration of the oil. Where does the wind come from? Pistons push air down into the crankcase as they move from top dead center to bottom dead center. The pistons also draw air and oil upward when moving from bottom dead center to top dead center. At high engine speeds, this causes a great deal of airflow, which can easily aerate the oil. Therefore, a windage tray is used to help prevent this movement of air (wind) from affecting the oil in the pan. Try the following: • Take an oil pan and add a few quarts (liters) of oil. • Then take an electric hair dryer and use it to blow air into the oil pan. Oil will be thrown everywhere, which helps illustrate why windage trays are used in all newer engines.

PURPOSE AND FUNCTION

The oil pan is where engine oil is used for lubricating the engine. Another name for the oil pan is a sump. As the vehicle accelerates, brakes, or turns rapidly, the oil tends to move around in the pan. Pan baffles and oil pan shapes are often used to keep the oil inlet under the oil at all times. As the crankshaft rotates, it acts like a fan and causes air within the crankcase to rotate with it. This can cause a strong draft on the oil, churning it so that air bubbles enter the oil, which then causes oil foaming. Oil with air will not lubricate like liquid oil, so oil foaming can cause bearings to fail. A baffle or windage tray is sometimes installed in engines to eliminate the oil churning problem. This may be an added part, as shown in FIGURE 23–16, or it may be a part of the oil pan. Windage trays have the good side effect of reducing the amount of air disturbed by the crankshaft, so that less power is drained from the engine at high crankshaft speeds.

DRY SUMP SYSTEM CONSTRUCTION AND OPERATION

The term sump is used to describe a location where oil is stored or held. In most engines, oil is held in the oil pan and the oil pump draws the oil from the

bottom. This type of system is called a wet sump oil system. In a dry sump system, the oil pan is shallow and the oil is pumped into a remote reservoir. In this reservoir, the oil is cooled and any trapped air is allowed to escape before being pumped back to the engine. A dry sump system uses an externally mounted oil reservoir.

ADVANTAGES

The advantages of a dry sump system are as

follows: 1. A shallow oil pan allows the engine to be mounted lower in the vehicle to improve cornering. 2. The oil capacity can be greatly expanded because the size of the reservoir is not limited. A larger quantity of oil means that the oil temperature can be controlled. 3. A dry sump system allows the vehicle to corner and brake for long periods, which is not able to be done with a wet sump system due to the oil being thrown to one side and away from the oil pickup. 4. A dry sump system also allows the engine to develop more power as the oil is kept away from the moving crankshaft.

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MAIN PRESSURE SUCTION

VALVE LIFTER

OIL COOLER

RETURN TO OIL TANK CAM BEARING OIL COOLER CRANK BEARING

OIL FILTER

OIL TANK OIL PUMP

FIGURE 23–18 Oil is cooled by the flow of coolant through the oil filter adapter. RELIEF VALVE OIL FILTER

OIL PICKUP

FIGURE 23–17 A dry sump system as used in a Chevrolet Corvette.

DISADVANTAGES

A dry sump system has the following

disadvantages. 1. The system is expensive as it requires components and plumbing not needed in a wet sump system. 2. The system is complex because the plumbing and connections, plus the extra components, result in more places where oil leaks can occur and change the way routine maintenance is handled. A dry sump oil system is used in most motor sport vehicles and is standard on certain high-performance production vehicles, such as some models of the Chevrolet Corvette, Porsche, and BMW. SEE FIGURE 23–17.

OIL COOLERS Oil temperature must be controlled on many high-performance or turbocharged engines. A larger capacity oil pan helps to control oil temperature. Some engines use remote mounted oil coolers. Coolant flows through the oil cooler to help warm the oil when the engine is cold and cool the oil when the engine is hot. Oil temperature should be:

Above 212°F (100°C) to boil off any accumulated moisture

Below 280°F to 300°F (138°C to 148°C)

?

FREQUENTLY ASKED QUESTION

What Is Acceptable Oil Consumption? There are a number of opinions regarding what is acceptable oil consumption. Most vehicle owners do not want their engine to use any oil between oil changes even if they do not change it more often than every 7,500 miles (12,000 km). Engineers have improved machining operations and piston ring designs to help eliminate oil consumption. Many stationary or industrial engines are not driven on the road, so they do not accumulate miles but still may consume excessive oil. A general rule for “acceptable” oil consumption is that it should be about 0.002 to 0.004 pound per horsepower per hour. To figure, use the following: 1.82 ⴛ Quarts used ⴝ Pound/hp/hr Operating hp ⴛ Total hours Therefore, oil consumption is based on the amount of work an engine performs. Although the formula may not be viable for vehicle engines used for daily transportation, it may be for the marine or industrial engine builder. Generally, oil consumption that is greater than 1 quart for every 600 miles (1 liter per 1,000 km) is considered to be excessive with a motor vehicle.

SEE FIGURE 23–18.

REVIEW QUESTIONS 1. What causes a wedge-shaped film to form in the oil? 2. What is hydrodynamic lubrication?

4. Describe how the oil flows from the oil pump, through the filter and main engine bearings, to the valve train.

6. What type of oil pump is driven by the crankshaft? a. Gerotor c. External gear b. Internal/external gear d. Both a and b

2. Two technicians are discussing oil pumps. Technician A says that many oil pumps are driven directly off the front of the crankshaft. Technician B says that some are driven from the distributor if the engine uses a distributor-type ignition system. Which technician is correct? a. Technician A only c. Both Technicians A and B b. Technician B only d. Neither Technician A nor B

7. Lower than specified oil pressure is measured on a high mileage engine. Technician A says that worn main or rod bearings could be the cause. Technician B says that a clogged oil pump pickup screen could be the cause. Which technician is correct? a. Technician A only c. Both Technicians A and B b. Technician B only d. Neither Technician A nor B

3. A typical oil pump can pump how many gallons per minute? a. 3 to 6 gallons b. 6 to 10 gallons c. 10 to 60 gallons d. 50 to 100 gallons 4. In typical engine lubrication systems, what components are the last to receive oil and the first to suffer from a lack of oil or oil pressure? a. Main bearings c. Valve train components b. Rod bearings d. Oil filters 5. Hydrodynamic lubrication is created by the wedging action of oil between the crankshaft journal and the bearing, can be as high as ______________ PSI. a. 60 c. 500 b. 120 d. 1,000

chapter

24

8. Oil passages in an engine block are usually called ______________. a. Galleries c. Runners b. Holes d. Pathways 9. Why is a dry sump system used in some high-performance vehicles? a. It allows the vehicle to corner or brake for long periods b. It allows the engine to develop more power c. It allows for a greater oil capacity so that oil temperatures can be controlled d. All of the above 10. An engine oil cooler uses what to cool the oil? a. Coolant b. Air c. Air-conditioning evaporator output d. Automatic transmission fluid after it flows through the radiator

1. Clean the air before it is mixed with fuel 2. Silence intake noise 3. Act as a flame arrester in case of a backfire

NEED FOR AIR FILTERING

Gasoline must be mixed with air to form a combustible mixture. Air movement into an engine occurs due to low pressure (vacuum) being created in the engine. SEE FIGURE 24–1. Air contains dirt and other materials that cannot be allowed to reach the engine. Just as fuel filters are used to clean impurities from gasoline, an air cleaner and filter are used to remove contaminants from the air. The three main jobs of the air cleaner and filter include:

The automotive engine uses about 9,000 gallons (34,000 liters) of air for every gallon of gasoline burned at an air-fuel ratio of 14.7:1 by weight. Without proper filtering of the air before it enters the engine, dust and dirt in the air can seriously damage engine parts and shorten engine life. Abrasive particles can cause wear any place inside the engine where two surfaces move against each other, such as piston rings against the cylinder wall. The dirt particles then pass by the piston rings and into the crankcase. From the crankcase, the particles

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INTAKE VALVE

ATMOSPHERIC PRESSURE LOW PRESSURE (VACUUM)

THROTTLE BODY

PISTON

CRANKSHAFT

MAF SENSOR

FIGURE 24–1 Downward movement of the piston lowers the air pressure inside the combustion chamber. The pressure differential between the atmosphere and the inside of the engine forces air into the engine.

FIGURE 24–3 Most air filter housings are located on the side of the engine compartment and use flexible rubber hose to direct the airflow into the throttle body of the engine. time intervals are based on so-called normal driving. More frequent air filter replacement is necessary when the vehicle is driven under dusty, dirty, or other severe conditions. It is best to replace a filter element before it becomes too dirty to be effective. A dirty air filter that passes contaminants can cause engine wear.

REMOTELY MOUNTED AIR FILTERS AND DUCTS

FIGURE 24–2 Dust and dirt in the air are trapped in the air filter so they do not enter the engine. circulate throughout the engine in the oil. Large amounts of abrasive particles in the oil can damage other moving engine parts. The filter that cleans the intake air is in a two-piece air cleaner housing made either of:

Stamped steel or

Composite (usually nylon reinforced plastic) materials.

AIR FILTER ELEMENTS

The paper air filter element is the most common type of filter. It is made of a chemically treated paper stock that contains tiny passages in the fibers. These passages form an indirect path for the airflow to follow. The airflow passes through several fiber surfaces, each of which traps microscopic particles of dust, dirt, and carbon. Most air filters are capable of trapping dirt and other particles larger than 10 to 25 microns in size. One micron is equal to 0.000039 in.

NOTE: A person can only see objects that are 40 microns or larger in size. A human hair is about 50 microns in diameter.

SEE FIGURE 24–2.

FILTER REPLACEMENT Manufacturers recommend cleaning or replacing the air filter element at periodic intervals, usually listed in terms of distance driven or months of service. The distance and

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Air cleaner and duct design depend on a number of factors such as the size, shape, and location of other engine compartment components, as well as the vehicle body structure. Port fuel-injection systems generally use a horizontally mounted throttle body. Some systems also have a mass airflow (MAF) sensor between the throttle body and the air cleaner. Because placing the air cleaner housing next to the throttle body would cause engine and vehicle design problems, it is more efficient to use this remote air cleaner placement. SEE FIGURE 24–3. Turbocharged engines present a similar problem. The air cleaner connects to the air inlet elbow at the turbocharger. However, the tremendous heat generated by the turbocharger makes it impractical to place the air cleaner housing too close to the turbocharger. Remote air cleaners are connected to the turbocharger air inlet elbow or fuel-injection throttle body by composite ducting that is usually retained by clamps. The ducting used may be rigid or flexible, but all connections must be airtight.

AIR FILTER RESTRICTION INDICATOR Some vehicles, especially pickup trucks that are often driven in dusty conditions, are equipped with an air filter restriction indicator. The purpose of this device is to give a visual warning when the air filter is restricted and needs to be replaced. The device operates by detecting the slight drop in pressure that occurs when an air filter is restricted. The calibration before the red warning bar or “replace air filter” message appears varies, but is usually:

15 to 20 in. of water (in. H2O) for gasoline engines

20 to 30 in. of water (in. H2O) for diesel engines

The unit of inches of water is used to measure the difference in air pressure before and after the air filter. The unit is very small, because 28 in. of water is equal to a pound per square inch (PSI). Some air filter restriction indicators, especially on diesel engines, include an electrical switch used to light a dash-mounted warning lamp when the air filter needs to be replaced. SEE FIGURE 24–4.

(a)

FIGURE 24–4 A typical air filter restriction indicator used on a General Motors truck engine. The indicator turns red when it detects enough restriction to require a filter replacement.

TECH TIP Always Check the Air Filter Always inspect the air filter and the air intake system carefully during routine service. Debris or objects deposited by animals can cause a restriction to the airflow and can reduce engine performance. SEE FIGURE 24–5. (b)

?

FREQUENTLY ASKED QUESTION

What Does This Tube Do? What is the purpose of the odd-shape tube attached to the inlet duct between the air filter and the throttle body, as seen in FIGURE 24–6? The tube shape is designed to dampen out certain resonant frequencies that can occur at specific engine speeds. The length and shape of this tube are designed to absorb shock waves that are created in the air intake system and to provide a reservoir for the air that will then be released into the airstream during cycles of lower pressure. This resonance tube is often called a Helmholtz resonator, named for the discoverer of the relationship between shape and value of frequency, Herman L. F. von Helmholtz (1821–1894) of the University of Hönizsberg in East Prussia. The overall effect of these resonance tubes is to reduce the noise of the air entering the engine.

THROTTLE-BODY INJECTION INTAKE MANIFOLDS TERMINOLOGY The intake manifold is also called an inlet manifold. Smooth engine operation can only occur when each combustion chamber produces the same pressure as every other chamber in the engine. For this to be achieved, each cylinder must receive an

FIGURE 24–5 (a) Note the discovery as the air filter housing was opened during service on a Pontiac. The nuts were obviously deposited by squirrels (or some other animal). (b) Not only was the housing filled with nuts, but also this air filter was extremely dirty, indicating that this vehicle had not been serviced for a long time.

RESONANCE TUBE

FIGURE 24–6 A resonance tube, called a Helmholtz resonator, is used on the intake duct between the air filter and the throttle body to reduce air intake noise during engine acceleration. intake charge exactly like the charge going into the other cylinders in quality and quantity. The charges must have the same physical properties and the same air-fuel mixture. A throttle-body fuel injector forces finely divided droplets of liquid fuel into the incoming air to form a combustible air-fuel mixture. SEE FIGURE 24–7 for an example of a typical throttle-body injection (TBI) unit.

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MAXIMUM MOTORING COMPRESSION (KPA)

FIGURE 24–7 A throttle-body injection (TBI) unit used on a GM V-6 engine.

FIGURE 24–9 The graph shows the effect of sonic tuning of the intake manifold runners. The longer runners increase the torque peak and move it to a lower RPM. The 600 mm intake runner is about 24 in. long.

PORT FUEL-INJECTION INTAKE MANIFOLDS TERMINOLOGY

FIGURE 24–8 Heavy fuel droplets separate as they flow around an abrupt bend in an intake manifold.

INTAKE AIR SPEEDS

These droplets start to evaporate as soon as they leave the throttle-body injector nozzles. The droplets stay in the charge as long as the charge flows at high velocities. At maximum engine speed, these velocities may reach 300 ft per second. Separation of the droplets from the charge as it passes through the manifold occurs when the velocity drops below 50 ft per second. Intake charge velocities at idle speeds are often below this value. When separation occurs—at low engine speeds—extra fuel must be supplied to the charge in order to have a combustible mixture reach the combustion chamber. Manifold sizes and shapes represent a compromise.

They must have a cross section large enough to allow charge flow for maximum power.

The cross section must be small enough that the flow velocities of the charge will be high enough to keep the fuel droplets in suspension. This is required so that equal mixtures reach each cylinder. Manifold cross-sectional size is one reason why engines designed especially for racing will not run at low engine speeds.

Racing manifolds must be large enough to reach maximum horsepower. This size, however, allows the charge to move slowly, and the fuel will separate from the charge at low engine speeds. Fuel separation leads to poor accelerator response. SEE FIGURE 24–8.

Standard passenger vehicle engines are primarily designed for economy during light-load, partial-throttle operation. Their manifolds, therefore, have a much smaller cross-sectional area than do those of racing engines. This small size will help keep flow velocities of the charge high throughout the normal operating speed range of the engine.

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The size and shape of port fuel-injected engine intake manifolds can be optimized because the only thing in the manifold is air. The fuel injector is located in the intake manifold about 3 to 4 in. (70 to 100 mm) from the intake valve. Therefore, the runner length and shape are designed for tuning only. There is no need to keep an air-fuel mixture thoroughly mixed (homogenized) throughout its trip from the TBI unit to the intake valve. Intake manifold runners are tuned to improve engine performance.

Long runners build low-RPM torque.

Shorter runners provide maximum high-RPM power.

SEE FIGURES 24–9 AND 24–10.

VARIABLE INTAKES Some engines with four valve heads utilize a dual or variable intake runner design. At lower engine speeds, long intake runners provide low-speed torque. At higher engine speeds, shorter intake runners are opened by means of a computercontrolled valve to increase high-speed power. Many intake manifolds are designed to provide both short runners best for higher engine speed power and longer runners best for lower engine speed torque. The valve(s) that control the flow of air through the passages of the intake manifold are computer controlled. SEE FIGURE 24–11. PLASTIC INTAKE MANIFOLDS

Most intake manifolds are made from thermoplastic molded from fiberglass-reinforced nylon by either casting or by injection molding. Some manifolds are molded in two parts and bonded together. Plastic intake manifolds are lighter than aluminum manifolds and can better insulate engine heat from the fuel injectors. Plastic intake manifolds have smoother interior surfaces than do other types of manifolds, resulting in greater airflow. SEE FIGURE 24–12.

UPPER AND LOWER INTAKE MANIFOLDS manifolds are constructed in two parts.

Many intake

IDLE AIR BYPASS VALVE THROTTLE

UPPER INTAKE MANIFOLD

PLENUM AREA FUEL PRESSURE RELIEF VALVE

AIR INTAKE

FIGURE 24–10 Airflow through the large diameter upper intake manifold is distributed to smaller diameter individual runners in the lower manifold in this two-piece manifold design.

LOWER INTAKE MANIFOLD

FUEL PRESSURE REGULATOR

FUEL RAIL

FUEL INJECTOR

A lower section attaches to the cylinder heads and includes passages from the intake ports.

An upper manifold, usually called the plenum, connects to the lower unit and includes the long passages needed to help provide the ram effect that helps the engine deliver maximum torque at low engine speeds. The throttle body attaches to the upper intake.

The use of a two-part intake manifold allows for easier manufacturing as well as assembly, but can create additional locations for leaks. If the lower intake manifold gasket leaks, not only could a vacuum leak occur affecting the operation of the engine, but a coolant leak or an oil leak can also occur if the manifold has coolant flowing through it. A leak at the gasket(s) of the upper intake manifold usually results in a vacuum (air) leak only.

FIGURE 24–11 The air flowing into the engine can be directed through long or short runners for best performance and fuel economy.

EXHAUST GAS RECIRCULATION PASSAGES PURPOSE AND FUNCTION To reduce the emission of oxides of nitrogen (NOx), engines have been equipped with exhaust gas recirculation (EGR) valves. From 1973 until recently, they were used on almost all vehicles. Most EGR valves are mounted on the intake manifold. Because of the efficiency of computer-controlled fuel injection, some newer engines do not require an EGR system to meet emission standards. These engines’ variable valve timing to close the exhaust valve sooner than normal, trapping some exhaust in the cylinder, is an alternative to using an EGR valve. On engines with EGR systems, the EGR valve opens at speeds above idle on a warm engine. When open, the valve allows a small portion of the exhaust gas (5% to 10%) to enter the intake manifold. The EGR system has some means of interconnecting of the exhaust and intake manifolds. The EGR valve controls the gas flow through the passages.

FIGURE 24–12 Many plastic intake manifolds are constructed using many parts glued together to form complex passages for airflow into the engine.

On V-type engines, the intake manifold crossover is used as a source of exhaust gas for the EGR system. A cast passage connects the exhaust crossover to the EGR valve.

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EGR VALVE

INTAKE VALVE CLOSED EXHAUST VALVE EXHAUST GASES

EXHAUST GAS TUBE

COMBUSTION CHAMBER PISTON

FIGURE 24–13 A typical long exhaust gas line used to cool the exhaust gases before being recirculated back into the intake manifold.

On inline-type engines, an external tube is generally used to carry exhaust gas to the EGR valve.

FIGURE 24–14 The exhaust gases are pushed out of the cylinder by the piston on the exhaust stroke.

EXHAUST GAS COOLERS The exhaust gases are more effective in reducing oxide of nitrogen (NOx) emissions if the exhaust is cooled before being drawn into the cylinders. This tube is often designed to be long so that the exhaust gas is cooled before it enters the EGR valve. SEE FIGURE 24–13.

EXHAUST MANIFOLDS PURPOSE AND FUNCTION

The exhaust manifold is designed to collect high-temperature spent gases from the individual head exhaust ports and direct them into a single outlet connected to the exhaust system. SEE FIGURE 24–14. The hot gases are sent to an exhaust pipe, then to a catalytic converter, to the muffler, to a resonator, and on to the tailpipe, where they are vented to the atmosphere. The exhaust system is designed to meet the following needs.

Provide the least possible amount of restriction or backpressure

Keep the exhaust noise at a minimum

Exhaust gas temperature will vary according to the power produced by the engine. The manifold must be designed to operate at both engine idle and continuous full power. Under full-power conditions, the exhaust manifold can become red-hot, causing a great deal of expansion. The temperature of an exhaust manifold can exceed 1,500°F (815°C).

CONSTRUCTION

Most exhaust manifolds are made from the

following:

Cast iron

Steel tubing

During vehicle operation, manifold temperatures usually reach the high-temperature extremes. The manifold is bolted to the head in a way that will allow expansion and contraction. In some cases, hollow-headed bolts are used to maintain a gas-tight seal while still allowing normal expansion and contraction.

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FIGURE 24–15 This exhaust manifold (red area) is equipped with a heat shield to help retain heat and reduce exhaust emissions.

Many exhaust manifolds have heat shields to help keep exhaust heat off the spark plug wires and to help keep the heat from escaping to improve exhaust emissions. SEE FIGURE 24–15. Exhaust systems are especially designed for the engine-chassis combination. The exhaust system length, pipe size, and silencer are designed, where possible, to make use of the tuning effect within the exhaust system. Tuning occurs when the exhaust pulses from the cylinders are emptied into the manifold between the pulses of other cylinders. SEE FIGURE 24–16.

EXHAUST MANIFOLD GASKETS

Exhaust heat will expand the manifold more than it will expand the head. The heat causes the exhaust manifold to slide on the sealing surface of the head. The heat also causes thermal stress. When the manifold is removed from the engine for service, the stress is relieved, which may cause the manifold to warp slightly. Exhaust manifold gaskets are included in gasket sets to seal slightly warped exhaust manifolds. These gaskets should be used, even if the engine did not originally use exhaust manifold gaskets. When an exhaust manifold gasket has facing on one side only, put the facing side against the head and put the manifold against the perforated metal core. The manifold can slide on the metal of the gasket just as it slid on the sealing surface of the head.

THREADED HOLE FOR OXYGEN SENSOR

CRACK

FIGURE 24–16 Many exhaust manifolds are constructed of steel tubing and are free flowing to improve engine performance.

?

FIGURE 24–17 A crack in an exhaust manifold is often not visible because a heat shield usually covers the area. A crack in the exhaust manifold upstream of the oxygen sensor can fool the sensor and affect engine operation.

FREQUENTLY ASKED QUESTION

How Can a Cracked Exhaust Manifold Affect Engine Performance? Cracks in an exhaust manifold will not only allow exhaust gases to escape and cause noise, but also allow air to enter the exhaust manifold. SEE FIGURE 24–17. Exhaust flows from the cylinders as individual puffs or pressure pulses. Behind each of these pressure pulses, a low pressure (below atmospheric pressure) is created. Outside air at atmospheric pressure is then drawn into the exhaust manifold through the crack. This outside air contains 21% oxygen and is measured by the oxygen sensor (O2S). The air passing the O2S signals the engine computer that the engine is operating too lean (excess oxygen) and the computer, not knowing that the lean indicator is false, adds additional fuel to the engine. The result is that the engine will be operating richer (more fuel than normal) and spark plugs could become fouled by fuel, causing poor engine operation.

FIGURE 24–18 Typical exhaust manifold gaskets. Note how they are laminated to allow the exhaust manifold to expand and contract due to heating and cooling.

TECH TIP Using the Correct Tool Saves Time

Gaskets are used on new engines with tubing- or header-type exhaust manifolds. They may have several layers of steel for hightemperature sealing. The layers are spot welded together. Some are embossed where special sealing is needed. SEE FIGURE 24–18. Many new engines do not use gaskets with cast exhaust manifolds. The flat surface of the new cast-iron exhaust manifold fits tightly against the flat surface of the new head.

MUFFLERS PURPOSE AND FUNCTION

When the exhaust valve opens, it rapidly releases high-pressure gas. This sends a strong air pressure wave through the atmosphere inside the exhaust system, which produces a sound we call an explosion. It is the same sound produced when the high-pressure gases from burned gunpowder are released from a gun. In an engine, the pulses are released one after another. The explosions come so fast that they blend together in a steady roar.

When cast-iron exhaust manifolds are removed, the stresses built up in the manifolds often cause the manifolds to twist or bend. This distortion even occurs when the exhaust manifolds have been allowed to cool before removal. Attempting to reinstall distorted exhaust manifolds is often a time-consuming and frustrating exercise. However, special spreading jacks can be used to force the manifold back into position so that the fasteners can be lined up with the cylinder head. SEE FIGURE 24–19.

Sound is air vibration. When the vibrations are large, the sound is loud. The muffler catches the large bursts of high-pressure exhaust gas from the cylinder, smoothing out the pressure pulses and allowing them to be released at an even and constant rate. It does this through the use of perforated tubes within the muffler chamber. The smoothflowing gases are released to the tailpipe. In this way, the muffler silences engine exhaust noise. SEE FIGURE 24–20.

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EXHAUST MANIFOLD SPREADER TOOL

FIGURE 24–19 An exhaust manifold spreader tool is absolutely necessary when reinstalling exhaust manifolds. When they are removed from the engine, the manifolds tend to warp slightly even though the engine is allowed to cool before being removed. The spreader tool allows the technician to line up the bolt holes without harming the manifold.

FIGURE 24–21 A hole in the muffler allows condensed water to escape.

FIGURE 24–20 Exhaust gases expand and cool as they travel through passages in the muffler.

?

FREQUENTLY ASKED QUESTION

Why Is There a Hole in My Muffler? Many mufflers are equipped with a small hole in the lower rear part to drain accumulated water. About 1 gallon of water is produced in the form of steam for each gallon of gasoline burned. The water is formed when gasoline is burned in the cylinder. Water consists of two molecules of hydrogen and one of oxygen (H2O). The hydrogen (H) comes from the fuel and the oxygen (O) comes from the air. During combustion, the hydrogen from the fuel combines with some of the oxygen in the air to form water vapor. The water vapor condenses on the cooler surfaces of the exhaust system, especially in the muffler, until the vehicle has been driven long enough to fully warm the exhaust above the boiling point of water (212°F [100°C]). SEE FIGURE 24–21.

CONSTRUCTION Most mufflers have a larger inlet diameter than outlet diameter. As the exhaust enters the muffler, it expands and cools. The cooler exhaust is denser and occupies less volume. The diameter of the outlet of the muffler and the diameter of the tailpipe can be reduced with no decrease in efficiency. Sometimes resonators are used in the exhaust system and the catalytic converter also acts as a muffler. They provide additional expansion space at critical points in the exhaust system to smooth out the exhaust gas flow. The tailpipe carries the exhaust gases from the muffler to the air, away from the vehicle. In most cases, the tailpipe exit is at the rear of the vehicle, below the rear bumper. In some cases, the exhaust is released at the side of the vehicle, just ahead of or just behind the rear wheel.

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FIGURE 24–22 A high-performance aftermarket air filter often can increase airflow into the engine for more power. HIGH-PERFORMANCE TIP More Airflow ⫽ More Power One of the most popular high-performance modifications is to replace the factory exhaust system with a low-restriction design and to replace the original air filter and air filter housing with a low-restriction unit, as shown in FIGURE 24–22. The installation of an aftermarket air filter not only increases power, but also increases air induction noise, which many drivers prefer. The aftermarket filter housing, however, may not be able to effectively prevent water from being drawn into the engine if the vehicle is traveling through deep water. Almost every modification that increases performance has a negative effect on some other part of the vehicle, or else the manufacturer would include the change at the factory.

The muffler and tailpipe are supported with brackets, called hangers, which help to isolate the exhaust noise from the rest of the vehicle. The types of exhaust system hangers include:

Rubberized fabric with metal ends that hold the muffler and tailpipe in position so that they do not touch any metal part, to isolate the exhaust noise from the rest of the vehicle

Rubber material that looks like large rubber bands, which slip over the hooks on the exhaust system and the hooks attached to the body of the vehicle

REVIEW QUESTIONS 1. Why is it necessary to have intake charge velocities of about 50 ft per second?

3. What is a tuned runner in an intake manifold? 4. How does a muffler quiet exhaust noise?

CHAPTER QUIZ 1. Intake charge velocity has to be ______________ to prevent fuel droplet separation. a. 25 ft per second c. 100 ft per second b. 50 ft per second d. 300 ft per second 2. The air filter restriction indicator uses what to detect when it signals to replace the filter? a. Number of hours of engine operation b. Number of miles of vehicle travel c. The amount of light that can pass through the filter d. The amount of restriction measured in inches of water 3. Why are the EGR gases cooled before entering the engine on some engines? a. Cool exhaust gas is more effective at controlling NOx emissions b. To help prevent the exhaust from slowing down c. To prevent damage to the intake valve d. To prevent heating the air-fuel mixture in the cylinder 4. The air-fuel mixture flows through the intake manifold on what type of system? a. Port fuel-injection systems b. Throttle-body fuel-injection systems c. Both a port-injected and throttle-body injected engine d. Any fuel-injected engine 5. Air filters can remove particles and dirt as small as ______________. a. 5 to 10 microns c. 30 to 40 microns b. 10 to 25 microns d. 40 to 50 microns

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25

6. Why do many port fuel-injected engines use long intake manifold runners? a. To reduce exhaust emissions b. To heat the incoming air c. To increase high-RPM power d. To increase low-RPM torque 7. Exhaust passages are included in some intake manifolds. Technician A says that the exhaust passages are used for exhaust gas recirculation (EGR) systems. Technician B says that the upper intake is often called the plenum. Which technician is correct? a. Technician A only c. Both Technicians A and B b. Technician B only d. Neither Technician A nor B 8. The upper portion of a two-part intake manifold is often called the ______________. a. Housing c. Plenum b. Lower part d. Vacuum chamber 9. Technician A says that a cracked exhaust manifold can affect engine operation. Technician B says that a leaking lower intake manifold gasket could cause a vacuum leak. Which technician is correct? a. Technician A only c. Both Technicians A and B b. Technician B only d. Neither Technician A nor B 10. Technician A says that some intake manifolds are plastic. Technician B says that some intake manifolds are constructed in two parts or sections: upper and lower. Which technician is correct? a. Technician A only c. Both Technicians A and B b. Technician B only d. Neither Technician A nor B

Naturally aspirated engines with throttle plates use atmospheric pressure to push an air-fuel mixture into the combustion chamber vacuum created by the down stroke of a piston. The mixture is then compressed before ignition to increase the force of the burning, expanding gases. The greater the compression of the air-fuel mixture, the higher the engine power output resulting from combustion. A four-stroke engine can take in only so much air, and how much fuel it needs for proper combustion depends on how much air it takes in. Engineers calculate engine airflow requirements using three factors.

VOLUMETRIC EFFICIENCY Volumetric efficiency is a measure of how well an engine breathes. It is a comparison of the actual volume of air-fuel mixture drawn into an engine to the theoretical maximum volume that could be drawn in. Volumetric efficiency is expressed as a percentage. If the engine takes in the airflow volume slowly, a cylinder might fill to capacity. It takes a definite amount of time for the airflow to pass through all the curves of the intake manifold and valve port. Therefore, volumetric efficiency decreases as engine speed increases due to the shorter amount of time for the cylinders to be filled with air during the intake stroke. At high speed, it may drop to as low as 50%. The average stock gasoline engine never reaches 100% volumetric efficiency. A new engine is about 85% efficient. A race engine usually has 95% or better volumetric efficiency. These figures apply only to naturally aspirated engines. However, with either turbochargers or superchargers, engines can easily achieve more than 100% volumetric efficiency. Many vehicles are equipped with a supercharger or a turbocharger from the factory to increase power. SEE FIGURES 25–1 AND 25–2.

FORCED INDUCTION PRINCIPLES

LOW DENSITY

HIGH DENSITY

FIGURE 25–3 The more air and fuel that can be packed in a cylinder, the greater the density of the air-fuel charge. the amount of the air-fuel charge introduced into the cylinders. Density is the mass of a substance in a given amount of space. SEE FIGURE 25–3. The greater the density of an air-fuel charge forced into a cylinder, the greater the force it produces when ignited, and the greater the engine power. An engine that uses atmospheric pressure for its intake charge is called a naturally (normally) aspirated engine. A better way to increase air density is to use some type of air pump such as a turbocharger or supercharger. When air is pumped into the cylinder, the combustion chamber receives an increase of air pressure known as boost, and can be measured in:

Pounds per square inch (PSI)

Atmospheres (ATM) (1 atmosphere is 14.7 PSI)

Bars (1 bar is 14.7 PSI)

While boost pressure increases air density, friction heats air in motion and causes an increase in temperature. This increase in temperature works in the opposite direction, decreasing air density. Because of these and other variables, an increase in pressure does not always result in greater air density.

PURPOSE AND FUNCTION

The amount of force an airfuel charge produces when it is ignited is largely a function of the charge density. Charge density is a term used to define

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FORCED INDUCTION PRINCIPLES

Forced induction systems use an air pump to pack a denser air-fuel charge into the

The effective compression ratio compared to the boost pressure. cylinders. Because the density of the air-fuel charge is greater, the following occurs.

The weight of the air-fuel charge is higher.

Power is increased because it is directly related to the weight of an air-fuel charge consumed within a given time period.

Pumping air into the intake system under pressure forces it through the bends and restrictions of the air intake system at a greater speed than it would travel under normal atmospheric pressure. This added pressure allows more air to enter the intake port before the intake valve closes. By increasing the airflow into the intake, more fuel can be mixed with the air while still maintaining the same air-fuel ratio. The denser the air-fuel charge entering the engine during its intake stroke, the greater the potential energy released during combustion. In addition to the increased power resulting from combustion, there are several other advantages of supercharging an engine, including:

It increases the air-fuel charge density to provide highcompression pressure when power is required, but allows the engine to run on lower pressures when additional power is not required. The pumped air pushes the remaining exhaust from the combustion chamber during intake and exhaust valve overlap. (Overlap is when both the intake and exhaust valves are partially open when the piston is near the top at the end of the exhaust stroke and the beginning of the intake stroke.)

The forced airflow and removal of hot exhaust gases lowers the temperature of the cylinder head, pistons, and valves, and helps extend the life of the engine.

A supercharger or turbocharger pressurizes air to greater than atmospheric pressure. The pressurization above atmospheric pressure, or boost, can be measured in the same way as atmospheric pressure. Atmospheric pressure drops as altitude increases, but boost pressure remains the same. If a supercharger develops 12 PSI (83 kPa) boost at sea level, it will develop the same amount at a 5,000 ft altitude because boost pressure is measured inside the intake manifold. SEE FIGURE 25–4.

BOOST AND COMPRESSION RATIOS Boost increases the amount of air drawn into the cylinder during the intake stroke. This extra air causes the effective compression ratio to be greater than the mechanical compression ratio designed into the engine. The higher the boost pressure, the greater the compression ratio. This means that any engine that uses a supercharger or turbocharger must use all of the following engine components.

Forged pistons, to withstand the increased combustion pressures

Stronger than normal connecting rods

Piston oil squirters that direct a stream of oil to the underneath part of the piston, to keep piston temperatures under control

Lower compression ratio compared to a naturally aspirated engine

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A centrifugal supercharger is not a positive displacement pump and all of the air that enters is not forced through the unit. Air enters a centrifugal supercharger housing in the center and exits at the outer edges of the compressor wheels at a much higher speed due to centrifugal force. The speed of the blades has to be higher than engine speed so a smaller pulley is used on the supercharger and the crankshaft overdrives the impeller through an internal gear box achieving about seven times the speed of the engine. Examples of centrifugal superchargers include Vortech and Paxton.

SUPERCHARGERS INTRODUCTION A supercharger is an engine-driven air pump that supplies more than the normal amount of air into the intake manifold and boosts engine torque and power. A supercharger provides an instantaneous increase in power without any delay. However, a supercharger, because it is driven by the engine, requires horsepower to operate and is not as efficient as a turbocharger. A supercharger is an air pump mechanically driven by the engine itself. Gears, shafts, chains, or belts from the crankshaft can all be used to turn the pump. This means that the air pump or supercharger pumps air in direct relation to engine speed. TYPES OF SUPERCHARGERS

There are two general types

of superchargers.

Roots type. Named for Philander and Francis Roots, two brothers from Connersville, Indiana, the roots supercharger was patented in 1860 as a type of water pump to be used in mines. Later, it was used to move air and is used today on two-stroke-cycle Detroit diesel engines and other supercharged engines. The roots-type supercharger is called a positive displacement design, because all of the air that enters is forced through the unit. Examples of a roots-type supercharger include the GMC 6-71 (used originally on GMC diesel engines that had 6 cylinders each with 71 cu. in.). Eaton used the roots design for the supercharger on the 3800 V-6 GM engine. SEE FIGURE 25–5. Centrifugal supercharger. A centrifugal supercharger is similar to a turbocharger, but is mechanically driven by the engine instead of being powered by the hot exhaust gases.

SUPERCHARGER BOOST CONTROL

Many factory installed superchargers are equipped with a bypass valve that allows intake air to flow directly into the intake manifold, bypassing the supercharger. The computer controls the bypass valve actuator. SEE FIGURE 25–6. The airflow is directed around the supercharger whenever any of the following conditions occur.

The boost pressure, as measured by the MAP sensor, indicates that the intake manifold pressure is reaching the predetermined boost level.

During deceleration, to prevent excessive pressure buildup in the intake.

Reverse gear is selected.

SUPERCHARGER SERVICE Superchargers are usually lubricated with synthetic engine oil inside the unit. This oil level should be checked and replaced as specified by the vehicle or supercharger manufacturer. The drive belt should also be inspected and replaced as necessary. The air filter should be replaced regularly, and always use the filter specified for a supercharged engine. Many factory supercharger systems use a separate cooling system for the air charge cooler located under the supercharger. Check service information for the exact service procedures to follow. SEE FIGURE 25–7.

TURBOCHARGERS LOBE

FIGURE 25–5 A roots-type supercharger uses two lobes to force the air around the outside of the housing and into the intake manifold.

INTRODUCTION The major disadvantage of a supercharger is it takes some of the engine power to drive the unit. In some installations, as much as 20% of the engine power is used by a mechanical supercharger. A turbocharger uses the heat of the exhaust to power

BYPASS ACTUATOR DRIVE PULLEY

TO VACUUM SOURCE (CONTROLLED BY THE COMPUTER)

SUPERCHARGER THROTTLE BODY

LOWER INTAKE PLEUM

BYPASS VALVE

FIGURE 25–6 The bypass actuator opens the bypass valve to control boost pressure.

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FUEL IN 100%

ROOTS-TYPE BLOWER

RADIATOR COOLING 25%

POWER OUT 25%

EXHAUST OUT 50%

FIGURE 25–8 A turbocharger uses some of the heat energy that would normally be wasted. EXHAUST

TURBINE WHEEL AIR CHARGE COOLER

FIGURE 25–7 A Ford supercharger cutaway display showing the roots-type blower and air charge cooler (intercooler). The air charge cooler is used to reduce the temperature of the compressed air before it enters the engine to increase the air charge density.

IMPELLER (COMPRESSOR) EXHAUST

TECH TIP Faster Moves More Air One of the high-performance measures that can be used to increase horsepower on a supercharged engine is to install a smaller diameter pulley. The smaller the pulley diameter, the faster the supercharger will rotate and the higher the potential boost pressure will be. The change will require a shorter belt, and the extra boost could cause serious engine damage.

a turbine wheel and therefore does not directly reduce engine power. In a naturally aspirated engine, about half of the heat energy contained in the fuel goes out the exhaust system. However, some engine power is lost due to the exhaust restriction. This loss in power is regained, though, to perform other work and the combustion heat energy lost in the engine exhaust (as much as 40% to 50%) can be harnessed to do useful work. Another 25% is lost through radiator cooling. Only about 25% is actually converted to mechanical power. A mechanically driven pump uses some of this mechanical output, but a turbocharger gets its energy from the exhaust gases, converting more of the fuel’s heat energy into useful mechanical energy. SEE FIGURE 25–8.

OPERATION A turbocharger turbine looks much like a typical centrifugal pump used for supercharging. Hot exhaust gases flow from the combustion chamber to the turbine wheel. The gases are heated and expanded as they leave the engine. It is not the speed of force of the exhaust gases that forces the turbine wheel to turn, as is commonly thought, but the expansion of hot gases against the turbine wheel’s blades. A turbocharger consists of two chambers connected with a center housing. The two chambers contain a turbine wheel and an impeller (compressor) wheel connected by a shaft which passes through the center housing. SEE FIGURE 25–9

FIGURE 25–9 A turbine wheel is turned by the expanding exhaust gases.

IMPELLER (COMPRESSOR)

TURBINE WHEEL

FIGURE 25–10 The exhaust drives the turbine wheel on the left which is connected to the impeller wheel on the right through a shaft. The bushings that support the shaft are lubricated with engine oil under pressure. To take full advantage of the exhaust heat which provides the rotating force, a turbocharger must be positioned as close as possible to the exhaust manifold. This allows the hot exhaust to pass directly into the unit with minimal heat loss. As exhaust gas enters the turbocharger, it rotates the turbine blades. The turbine wheel and compressor wheel are on the same shaft so that they turn at the same speed. Rotation of the compressor wheel draws air in through a central inlet and centrifugal force pumps it through an outlet at the edge of the housing. A pair of bearings in the center housing supports the turbine and compressor wheel shaft, and is lubricated by engine oil. SEE FIGURE 25–10.

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OIL LINE TO TURBOCHARGER BUSHINGS

TURBINE (EXHAUST SIDE)

IMPELLER (AIR SIDE)

FIGURE 25–11 Engine oil is fed to the center of the turbocharger to lubricate the bushings and returns to the oil pan through a return line.

Both the turbine and compressor wheels must operate with extremely close clearances to minimize possible leakage around their blades. Any leakage around the turbine blades causes a dissipation of the heat energy required for compressor rotation. Leakage around the compressor blades prevents the turbocharger from developing its full boost pressure.

TURBOCHARGER OPERATION When the engine is started and runs at low speed, both exhaust heat and pressure are low and the turbine runs at a low speed (approximately 1000 RPM). Because the compressor does not turn fast enough to develop boost pressure, air simply passes through it and the engine works like any naturally aspirated engine. As the engine runs faster or load increases, both exhaust heat and flow increase, causing the turbine and compressor wheels to rotate faster. Since there is no brake and very little rotating resistance on the turbocharger shaft, the turbine and compressor wheels accelerate as the exhaust heat energy increases. When an engine is running at full power, the typical turbocharger rotates at speeds between 100,000 and 150,000 RPM. The turbocharger is lubricated by engine oil through an oil line to the center bearing assembly. SEE FIGURE 25–11. Engine deceleration from full power to idle requires only a second or two because of its internal friction, pumping resistance, and drivetrain load. The turbocharger, however, has no such load on its shaft, and is already turning many times faster than the engine at top speed. As a result, it can take as much as a minute or more after the engine has returned to idle speed before the turbocharger also has returned to idle. If the engine is decelerated to idle and then shut off immediately, engine lubrication stops flowing to the center housing bearings while the turbocharger is still spinning at thousands of RPM. The oil in the center housing is then subjected to extreme heat and can gradually “coke” or oxidize. The coked oil can clog passages and will reduce the life of the turbocharger. The high rotating speeds and extremely close clearances of the turbine and compressor wheels in their housings require equally critical bearing clearances. The bearings must keep radial clearances of 0.003 to 0.006 in. (0.08 to 0.15 mm). Axial clearance (endplay) must be maintained at 0.001 to 0.003 in. (0.025 to 0.08 mm). If properly maintained, the turbocharger also is a trouble-free device. However, to prevent problems, the following must be met.

The turbocharger bearings must be constantly lubricated with clean engine oil. Turbocharged engines usually have specified

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oil changes at more frequent intervals than nonturbocharged engines. Always use the specified engine oil, which is likely to be vehicle specific and synthetic.

Dirt particles and other contamination must be kept out of the intake and exhaust housings.

Whenever a basic engine bearing (crankshaft or camshaft) has been damaged, the turbocharger must be flushed with clean engine oil after the bearing has been replaced.

If the turbocharger is damaged, the engine oil must be drained and flushed and the oil filter replaced as part of the repair procedure.

Late-model turbochargers all have liquid-cooled center bearings to prevent heat damage. In a liquid-cooled turbocharger, engine coolant is circulated through passages cast in the center housing to draw off the excess heat. This allows the bearings to run cooler and minimize the probability of oil coking when the engine is shut down.

TURBOCHARGER SIZE AND RESPONSE TIME A time lag occurs between an increase in engine speed and the increase in the speed of the turbocharger. This delay between acceleration and turbo boost is called turbo lag. Like any material, moving exhaust gas has inertia. Inertia also is present in the turbine and compressor wheels, as well as the intake airflow. Unlike a supercharger, the turbocharger cannot supply an adequate amount of boost at low speed. Turbocharger response time is directly related to the size of the turbine and compressor wheels. Small wheels accelerate rapidly; large wheels accelerate slowly. While small wheels would seem to have an advantage over larger ones, they may not have enough airflow capacity for an engine. To minimize turbo lag, the intake and exhaust breathing capacities of an engine must be matched to the exhaust and intake airflow capabilities of the turbocharger.

BOOST CONTROL PURPOSE AND FUNCTION Both supercharged and turbocharged systems are designed to provide a pressure greater than atmospheric pressure in the intake manifold. This increased pressure forces additional amounts of air into the combustion chamber over what would normally be forced in by atmospheric pressure. This increased charge increases engine power. The amount of “boost” (or pressure in the intake manifold) is measured in pounds per square inch (PSI), in inches of mercury (in. Hg), in bars, or in atmospheres. The following values will vary due to altitude and weather conditions (barometric pressure). 1 atmosphere ⫽ 14.7 PSI 1 atmosphere ⫽ 29.50 in. Hg 1 atmosphere ⫽ 1 bar 1 bar ⫽ 14.7 PSI

BOOST CONTROL FACTORS

The higher the level of boost (pressure), the greater the horsepower output potential. However, other factors must be considered when increasing boost pressure. 1. As boost pressure increases, the temperature of the air also increases. 2. As the temperature of the air increases, combustion temperatures also increase, as well as the possibility of detonation. 3. Power can be increased by cooling the compressed air after it leaves the turbocharger. The power can be increased about

1% per 10°F by which the air is cooled. A typical cooling device is called an intercooler. It is similar to a radiator, wherein outside air can pass through, cooling the pressurized heated air. An intercooler is located between the turbocharger and the intake manifold. SEE FIGURE 25–12. Some intercoolers use engine coolant to cool the hot compressed air that flows from the turbocharger to the intake.

4. As boost pressure increases, combustion temperature and pressures increase, which, if not limited, can do severe engine damage. The maximum exhaust gas temperature must be 1,550°F (840°C). Higher temperatures decrease the durability of the turbocharger and the engine.

WASTEGATE Turbochargers use exhaust gases to increase boost, which causes the engine to make more exhaust gases, which in turn increases the boost from the turbocharger. To prevent overboost and severe engine damage, most turbocharger systems use a wastegate. A wastegate is a valve similar to a door that can open and close. It is a bypass valve at the exhaust inlet to the turbine, which allows all of the exhaust into the turbine, or it can route part of the exhaust past the turbine to the exhaust system. If the valve is closed, all of the exhaust travels to the turbocharger. When a predetermined amount of boost pressure develops in the intake manifold, the wastegate valve is opened. As the valve opens, most of the exhaust flows directly out the exhaust system, bypassing the turbocharger. With less exhaust flowing across the vanes of the turbocharger, the turbocharger decreases in speed, and boost pressure is reduced. When the boost pressure drops, the wastegate valve closes to direct the exhaust over the turbocharger vanes to again allow the boost pressure to rise. Wastegate operation is a continuous process to control boost pressure. The wastegate is the pressure control valve of a turbocharger system. It is usually controlled by the engine control computer through a boost control solenoid, also called a wastegate control valve. SEE FIGURE 25–13.

FIGURE 25–12 The unit on top of this Subaru that looks like a radiator is the intercooler, which cools the air after it has been compressed by the turbocharger.

WASTEGATE CONTROL VALVE (N.C.) VENT TO AIR CLEANER

PCM IGN.

BOOST PRESSURE

WASTEGATE (OPEN)

INTAKE EXHAUST STROKE

COMPRESSOR

TURBINE

EXHAUST

FIGURE 25–13 A wastegate is used on many turbocharged engines to control maximum boost pressure. The wastegate is controlled by a computer-controlled valve.

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RELIEF VALVES

A wastegate controls the exhaust side of the turbocharger. A relief valve controls the intake side. A relief valve vents pressurized air from the connecting pipe between the outlet of the turbocharger and the throttle whenever the throttle is closed during boost, such as during shifts. If the pressure is not released, the turbocharger turbine wheel will slow down, creating a lag when the throttle is opened again after a shift has been completed. There are two basic types of relief valves. 1. Compressor bypass valve (CBV). This type of relief valve routes the pressurized air to the inlet side of the turbocharger for reuse and is quiet during operation. 2. Blow-off valve (BOV). Also called a dump valve or vent valve, the BOV features an adjustable spring design that keeps the

TECH TIP Boost Is the Result of Restriction The boost pressure of a turbocharger (or supercharger) is commonly measured in pounds per square inch. If a cylinder head is restricted because of small valves and ports, the turbocharger will quickly provide boost. Boost results when the air being forced into the cylinder heads cannot flow into the cylinders fast enough and “piles up” in the intake manifold, increasing boost pressure. If an engine had large valves and ports, the turbocharger could provide a much greater amount of air into the engine at the same boost pressure as an identical engine with smaller valves and ports. Therefore, by increasing the size of the valves, a turbocharged or supercharged engine will be capable of producing much greater power.

valve closed until a sudden release of the throttle. The resulting pressure increase opens the valve and vents the pressurized air directly into the atmosphere. This type of relief valve is noisy in operation and creates a whooshing sound when the valve opens. SEE FIGURE 25–14.

TURBOCHARGER FAILURES SYMPTOMS OF FAILURE

When turbochargers fail to function correctly, a noticeable drop in power occurs. To restore proper operation, the turbocharger must be rebuilt, repaired, or replaced. It is not possible to simply remove the turbocharger, seal any openings, and maintain decent driveability. Bearing failure is a common cause of turbocharger failure, and replacement bearings are usually only available to rebuilders. Another common turbocharger problem is excessive and continuous oil consumption resulting in blue

TECH TIP If One Is Good, Two Are Better A turbocharger uses the exhaust from the engine to spin a turbine, which is connected to an impeller inside a turbocharger. This impeller then forces air into the engine under pressure, higher than is normally achieved without a turbocharger. The more air that can be forced into an engine, the greater the power potential. A V-type engine has two exhaust manifolds and so two small turbochargers can be used to help force greater quantities of air into an engine, as shown in FIGURE 25–15.

SPRING

RELIEF VALVE THROTTLE VALVE (CLOSED)

BLOWOFF VALVE BOOST PRESSURE

WASTEGATE (CLOSED)

INTAKE EXHAUST STROKE

COMPRESSOR

TURBINE

EXHAUST

FIGURE 25–14 A blow-off valve is used in some turbocharged systems to relieve boost pressure during deceleration.

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FIGURE 25–15 A dual turbocharger system installed on a small block Chevrolet V-8 engine. exhaust smoke. Turbochargers use small rings similar to piston rings on the shaft to prevent exhaust (combustion gases) from entering the central bearing. Because there are no seals to keep oil in, excessive oil consumption is usually caused by the following: 1. Plugged positive crankcase ventilation (PCV) system, resulting in excessive crankcase pressures forcing oil into the air inlet (This failure is not related to the turbocharger, but the turbocharger is often blamed.) 2. Clogged air filter, which causes a low-pressure area in the inlet, drawing oil past the turbo shaft rings and into the intake manifold. 3. Clogged oil return (drain) line from the turbocharger to the oil pan (sump), which can cause the engine oil pressure to force oil past the turbocharger’s shaft rings and into the intake and exhaust manifolds (Obviously, oil being forced into both the intake and exhaust would create lots of smoke.)

PREVENTING TURBOCHARGER FAILURES To help prevent turbocharger failures, the wise vehicle owner should follow the vehicle manufacturer’s recommended routine service procedures. The most critical of these services include:

Regular oil changes (synthetic oil would be best)

Regular air filter replacement intervals

Performing any other inspections and services recommended such as cleaning the intercooler.

NITROUS OXIDE INTRODUCTION Nitrous oxide is used for racing or highperformance only, and is not used from the factory on any vehicle. This system is a relatively inexpensive way to get additional power from an engine, but can cause serious engine damage if not used correctly or in excess amounts, or without proper precautions. PRINCIPLES Nitrous oxide (N2O) is a colorless, nonflammable gas. It was discovered by a British chemist, Joseph Priestly (1733–1804), who also discovered oxygen. Priestly found that if a person breathed in nitrous oxide, it caused light-headedness, and so the gas soon became known as laughing gas. Nitrous oxide

TEMPERATURE (°F/°C)

PRESSURE (PSI/KPA)

⫺30°F/⫺34°C

67 PSI/468 kPa

⫺20°F/⫺29°C

203 PSI/1,400 kPa

⫺10°F/⫺23°C

240 PSI/1,655 kPa

0°F/⫺18°C

283 PSI/1,950 kPa

10°F/⫺12°C

335 PSI/2,310 kPa

20°F/⫺7°C

387 PSI/2,668 kPa

30°F/⫺1°C

460 PSI/3,172 kPa

40°F/4°C

520 PSI/3,585 kPa

50°F/10°C

590 PSI/4,068 kPa

60°F/16°C

675 PSI/4,654 kPa

70°F/21°C

760 PSI/5,240 kPa

80°F/27°C

865 PSI/5,964 kPa

90°F/32°C

985 PSI/6,792 kPa

100°F/38°C

1,120 PSI/7,722 kPa

CHART 25–2 Temperature/pressure relation for nitrous oxide: The higher the temperature, the higher the pressure.

was used in dentistry during tooth extractions to reduce the pain and cause the patient to forget the experience. Nitrous oxide has two nitrogen atoms and one oxide atom. About 36% of the molecule weight is oxygen. Nitrous oxide is a manufactured gas because, even though both nitrogen and oxygen are present in our atmosphere, they are not combined into one molecule and require heat and a catalyst to be combined.

ENGINE POWER ADDER

A power adder is a device or system added to an engine, such as a supercharger, turbocharger, or nitrous oxide, to increase power. When nitrous oxide is injected into an engine along with gasoline, engine power is increased. The addition of N2O supplies the needed oxygen for the extra fuel. N2O by itself does not burn, but provides the oxygen for additional fuel that is supplied along with the N2O to produce more power. NOTE: Nitrous oxide was used as a power adder in World War II on some fighter aircraft. Having several hundred more horsepower for a short time saved many lives.

PRESSURE AND TEMPERATURE It requires about 11 lb of pressure per degree Fahrenheit to condense nitrous oxide gas into liquid nitrous oxide. For example, at 70°F, it requires a pressure of about 770 PSI to condense N2O into a liquid. To change N2O from a liquid under pressure to a gas, all that is needed is to lower its pressure below the pressure it takes to cause it to become a liquid. The temperature also affects the pressure of N2O. SEE CHART 25–2. Nitrous oxide is stored in a pressurized storage container and installed at an angle so the pickup tube is in the liquid. The front or discharge end of the storage bottle should be toward the front of the vehicle. SEE FIGURE 25–16. WET AND DRY SYSTEM There are two different types of N2O systems that depend on whether additional fuel (gasoline) is supplied at the same time as when the nitrous oxide is squirted.

The wet system involves additional fuel being injected. It is identified as having both a red and a blue nozzle, with the red flowing gasoline and the blue flowing nitrous oxide.

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THIS SIDE UP

FRONT OF VEHICLE

LIQUID N2O

FIGURE 25–16 Nitrous bottles have to be mounted at an angle to ensure that the pickup tube is in the liquid N2O.

In a dry system, such as an engine using port fuel injection, only nitrous oxide needs to be injected because the PCM can be commanded to provide more fuel when the N2O is being sprayed. As a result, the intake manifold contains only air and the injected gaseous N2O.

FIGURE 25–17 An electrical heating mat is installed on the bottle of nitrous oxide to increase the pressure of the gas inside. TECH TIP

ENGINE CHANGES NEEDED FOR N2O

If nitrous oxide is going to be used to increase horsepower more than 50 hp, the engine must be designed and built to withstand the greater heat and pressure that will occur in the combustion chambers. For example, the following items should be considered if adding a turbocharger, supercharger, or nitrous oxide system.

Forged pistons are best able to withstand the pressure and temperature when using nitrous oxide or other power adder.

Cylinder-to-wall clearance should be increased. Due to the greater amount of heat created by the extra fuel and N2O injection, the piston temperature will be increased. Although using forged pistons will help, most experts recommend using increased cylinder-to-wall clearance.

Using forged crankshaft and connecting rods.

Check the instructions from the nitrous oxide supplier for details and other suggested changes. CAUTION: The use of a nitrous oxide injection system can cause catastrophic engine damage. Always follow the instructions that come with the kit and be sure that all of the internal engine parts meet the standard specified to help avoid severe engine damage.

Increase Bottle Pressure To increase the pressure of the nitrous oxide in a bottle, an electrical warming blanket can be used, as seen in FIGURE 25–17. The higher the temperature, the higher the pressure and the greater the amount of N2O flow when energized.

SYSTEM INSTALLATION AND CALIBRATION

Nitrous oxide systems are usually purchased as a kit with all of the needed components included. The kit also includes one or more sizes of nozzle(s), which are calibrated to control the flow of nitrous oxide into the intake manifold. The sizes of the nozzles are often calibrated in horsepower that can be gained by their use. Commonly sized nozzles include:

50 hp

100 hp

150 hp

Installation of a nitrous oxide kit also includes the installation of an on-off switch and a switch on or near the throttle, which is used to activate the system only when the throttle is fully opened (WOT).

REVIEW QUESTIONS 1. What are the reasons why supercharging increases engine power? 2. How does the bypass valve work on a supercharged engine?

4. What are the advantages and disadvantages of turbocharging? 5. What turbocharger control valves are needed for proper engine operation?

2. Two types of superchargers include ______________. a. Rotary and reciprocating c. Double and single acting b. Roots-type and centrifugal d. Turbine and piston

3. Which valve is used on a factory supercharger to limit boost? a. Bypass valve c. Blow-off valve b. Wastegate d. Air valve 4. How are most superchargers lubricated? a. By engine oil under pressure through lines from the engine b. By an internal oil reservoir c. By greased bearings d. No lubrication is needed because the incoming air cools the supercharger

7. What is the purpose of an intercooler? a. To reduce the temperature of the air entering the engine b. To cool the turbocharger c. To cool the engine oil on a turbocharged engine d. To cool the exhaust before it enters the turbocharger 8. Which type of relief valve used on a turbocharged engine is noisy? a. Bypass valve c. Dump valve b. BOV d. Both b and c

5. How are most turbochargers lubricated? a. By engine oil under pressure through lines from the engine b. By an internal oil reservoir c. By greased bearings d. No lubrication is needed because the incoming air cools the supercharger

9. Technician A says that a stuck open wastegate can cause the engine to burn oil. Technician B says that a clogged PCV system can cause the engine to burn oil. Which technician is correct? a. Technician A only c. Both Technicians A and B b. Technician B only d. Neither Technician A nor B

6. Two technicians are discussing the term turbo lag. Technician A says that it refers to the delay between when the exhaust leaves the cylinder and when it contacts the turbine blades of the turbocharger. Technician B says that it refers to the delay in boost pressure that occurs when the throttle is first opened. Which technician is correct? a. Technician A only c. Both Technicians A and B b. Technician B only d. Neither Technician A nor B

10. What service operation is most important on engines equipped with a turbocharger? a. Replacing the air filter regularly b. Replacing the fuel filter regularly c. Regular oil changes d. Regular exhaust system maintenance

If there is an engine operation problem, then the cause could be any one of many items, including the engine itself. The condition of the engine should be tested anytime the operation of the engine is not satisfactory.

TYPICAL ENGINE-RELATED COMPLAINTS Many driveability problems are not caused by engine mechanical problems. A thorough inspection and testing of the ignition and fuel systems should be performed before testing for mechanical engine problems.

FIGURE 26–1 Blowby gases coming out of the crankcase vent hose. Excessive amounts of combustion gases flow past the piston rings and into the crankcase.

FIGURE 26–2 White steam is usually an indication of a blown (defective) cylinder head gasket that allows engine coolant to flow into the combustion chamber where it is turned to steam.

Typical Exhaust Smoke Color

Possible Causes

Blue

Blue exhaust indicates that the engine is burning oil. Oil is getting into the combustion chamber either past the piston rings or past the valve stem seals. Blue smoke only after start-up is usually due to defective valve stem seals. SEE FIGURE 26–1.

Black

Black exhaust smoke is due to excessive fuel being burned in the combustion chamber. Typical causes include a defective or misadjusted throttle body, leaking fuel injector, or excessive fuelpump pressure.

White (steam)

White smoke or steam from the exhaust is normal during cold weather and represents condensed steam. Every engine creates about 1 gallon of water for each gallon of gasoline burned. If the steam from the exhaust is excessive, then water (coolant) is getting into the combustion chamber. Typical causes include a defective cylinder head gasket, a cracked cylinder head, or in severe cases a cracked block. SEE FIGURE 26–2.

Note: White smoke can also be created when automatic transmission fluid (ATF) is burned. A common source of ATF getting into the engine is through a defective vacuum modulator valve on older automatic transmissions.

OIL LEVEL AND CONDITION

THE DRIVER IS YOUR BEST RESOURCE The driver of the vehicle knows a lot about the vehicle and how it is driven. Before diagnosis is started, always ask the following questions.

When did the problem first occur? Under what conditions does it occur? 1. Cold or hot? 2. Acceleration, cruise, or deceleration? 3. How far was it driven? 4. What recent repairs have been performed?

After the nature and scope of the problem are determined, the complaint should be verified before further diagnostic tests are performed.

VISUAL CHECKS The first and most important “test” that can be performed is a careful visual inspection.

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The first area for visual inspec-

tion is oil level and condition. 1. Oil level—oil should be to the proper level 2. Oil condition a. Using a match or lighter, try to light the oil on the dipstick; if the oil flames up, gasoline is present in the engine oil. b. Drip some of the engine oil from the dipstick onto the hot exhaust manifold. If the oil bubbles or boils, there is coolant (water) in the oil. c. Check for grittiness by rubbing the oil between your fingers.

COOLANT LEVEL AND CONDITION Most mechanical engine problems are caused by overheating. The proper operation of the cooling system is critical to the life of any engine. NOTE: Check the coolant level in the radiator only if the radiator is cool. If the radiator is hot and the radiator cap is removed, the drop in pressure above the coolant will cause the coolant to boil immediately and can cause severe burns when the coolant explosively expands upward and outward from the radiator opening. 1. The coolant level in the coolant recovery container should be within the limits indicated on the overflow bottle. If this level is too low or the coolant recovery container is empty, then check the level of coolant in the radiator (only when cool) and also check the operation of the pressure cap.

HARMONIC BALANCER

OIL PAN

FIGURE 26–3 What looks like an oil pan gasket leak can be a rocker cover gasket leak. Always look up and look for the highest place you see oil leaking; that should be repaired first.

TECH TIP Your Nose Knows Whenever diagnosing any vehicle try to use all senses including smell. Some smells and their cause include: • Gasoline. If the exhaust smells like gasoline or unburned fuel, then a fault with the ignition system is a likely cause. Unburned fuel due to lean air-fuel mixture causing a lean misfire is also possible. • Sweet smell. A coolant leak often gives off a sweet smell especially if the leaking coolant flows onto the hot exhaust. • Exhaust smell. Check for an exhaust leak including a possible cracked exhaust manifold which can be difficult to find because it often does not make noise.

2. The coolant should be checked with a hydrometer for boiling and freezing temperature. This test indicates if the concentration of the antifreeze is sufficient for proper protection. 3. Pressure test the cooling system and look for leakage. Coolant leakage can often be seen around hoses or cooling system components because it will often cause: a. A grayish white stain b. A rusty color stain c. Dye stains from antifreeze (greenish or yellowish depending on the type of coolant)

FIGURE 26–4 The transmission and flexplate (flywheel) were removed to check the exact location of this oil leak. The rear main seal and/or the oil pan gasket could be the cause of this leak.

TECH TIP What’s Leaking? The color of the leaks observed under a vehicle can help the technician determine and correct the cause. Some leaks, such as condensate (water) from the air-conditioning system, are normal, whereas a brake fluid leak is very dangerous. The following are colors of common leaks. Sooty Black

Oil leaks can lead to severe engine damage if the resulting low oil level is not corrected. Besides causing an oily mess where the vehicle is parked, the oil leak can cause blue smoke to occur under the hood as leaking oil drips on the exhaust system. Finding the location of the oil leak can often be difficult. SEE FIGURES 26–3 AND 26–4. To help find the source of oil leaks follow these steps: STEP 1

Clean the engine or area around the suspected oil leak. Use a high-powered hot-water spray to wash the engine. While

the engine is running, spray the entire engine and the engine compartment. Avoid letting the water come into direct contact with the air inlet and ignition distributor or ignition coil(s). NOTE: If the engine starts to run rough or stalls when the engine gets wet, then the secondary ignition wires (spark plug wires) or distributor cap may be defective or have weak insulation. Be certain to wipe all wires and the distributor cap dry with a soft, dry cloth if the engine stalls. An alternative method is to spray a degreaser on the engine, then start and run the engine until warm. Engine heat helps

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FIGURE 26–5 Using a black light to spot leaks after adding dye to the oil. the degreaser penetrate the grease and dirt. Use a water hose to rinse off the engine and engine compartment. STEP 2

STEP 3

FIGURE 26–6 An accessory belt tensioner. Most tensioners have a mark that indicates normal operating location. If the belt has stretched, this indicator mark will be outside of the normal range. Anything wrong with the belt or tensioner can cause noise.

If the oil leak is not visible or oil seems to be coming from “everywhere,” use a white talcum powder. The leaking oil will show as a dark area on the white powder. See the Tech Tip, “The Foot Powder Spray Trick.”

TECH TIP The Foot Powder Spray Trick

Fluorescent dye can be added to the engine oil. Add about 1/2 oz (15 cc) of dye per 5 quarts of engine oil. Start the engine and allow it to run about 10 minutes to thoroughly mix the dye throughout the engine. A black light can then be shown around every suspected oil leak location. The black light will easily show all oil leak locations because the dye will show as a bright yellow/green area. SEE FIGURE 26–5.

The source of an oil or other fluid leak is often difficult to determine. A quick and easy method that works is the following. First, clean the entire area. This can best be done by using a commercially available degreaser to spray the entire area. Let it soak to loosen all accumulated oil and greasy dirt. Clean off the degreaser with a water hose. Let the area dry. Start the engine, and using spray foot powder or other aerosol powder product, spray the entire area. The leak will turn the white powder dark. The exact location of any leak can be quickly located.

NOTE: Fluorescent dye works best with clean oil.

ENGINE NOISE DIAGNOSIS

NOTE: Most oil leaks appear at the bottom of the engine due to gravity. Look for the highest, most forward location for the source of the leak.

An engine knocking noise is often difficult to diagnose. Several items that can cause a deep engine knock include:

Valves clicking. This can happen because of lack of oil to the lifters. This noise is most noticeable at idle when the oil pressure is the lowest. Torque converter. The attaching bolts or nuts may be loose on the flex plate. This noise is most noticeable at idle or when there is no load on the engine.

Cracked flex plate. The noise of a cracked flex plate is often mistaken for a rod- or main-bearing noise.

Loose or defective drive belts or tensioners. If an accessory drive belt is loose or defective, the flopping noise often sounds similar to a bearing knock. SEE FIGURE 26–6.

Piston pin knock. This knocking noise is usually not affected by load on the cylinder. If the clearance is too great, a double knock noise is heard when the engine idles. If all cylinders are grounded out one at a time and the noise does not change, a defective piston pin could be the cause.

Piston slap. A piston slap is usually caused by an undersized or improperly shaped piston or oversized cylinder bore. A

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piston slap is most noticeable when the engine is cold and tends to decrease or stop making noise as the piston expands during engine operation.

Timing chain noise. An excessively loose timing chain can cause a severe knocking noise when the chain hits the timing chain cover. This noise can often sound like a rod-bearing knock.

Rod-bearing noise. The noise from a defective rod bearing is usually load sensitive and changes in intensity as the load on the engine increases and decreases. A rod-bearing failure can often be detected by grounding out the spark plugs one cylinder at a time. If the knocking noise decreases or is eliminated when a particular cylinder is grounded (disabled), then the grounded cylinder is the one from which the noise is originating.

Main-bearing knock. A main-bearing knock often cannot be isolated to a particular cylinder. The sound can vary in intensity and may disappear at times depending on engine load.

Regardless of the type of loud knocking noise, after the external causes of the knocking noise have been eliminated, the engine should be disassembled and carefully inspected to determine the exact cause.

TECH TIP Engine Noise and Cost A light ticking noise often heard at one-half engine speed and associated with valve train noise is a less serious problem than many deep-sounding knocking noises. Generally, the deeper the sound of the engine noise, the more the owner will have to pay for repairs. A light “tick tick tick,” though often not cheap, is usually far less expensive than a deep “knock knock knock” from the engine.

OIL PRESSURE TESTING Proper oil pressure is very important for the operation of any engine. Low oil pressure can cause engine wear, and engine wear can cause low oil pressure. If main thrust or rod bearings are worn, oil pressure is reduced because of leakage of the oil around the bearings. Oil pressure testing is usually performed with the following steps. STEP 1

Operate the engine until normal operating temperature is achieved.

STEP 2

With the engine off, remove the oil pressure sending unit or sender, usually located near the oil filter. Thread an oil pressure gauge into the threaded hole. SEE FIGURE 26–8. NOTE: An oil pressure gauge can be made from another gauge, such as an old air-conditioning gauge and a flexible brake hose. The threads are often the same as those used for the oil pressure sending unit.

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TECH TIP Use the KISS Test Method Engine testing is done to find the cause of an engine problem. All the simple things should be tested first. Just remember KISS—“keep it simple, stupid.” A loose alternator belt or loose bolts on a torque converter can sound just like a lifter or rod bearing. A loose spark plug can make the engine perform as if it had a burned valve. Some simple items that can cause serious problems include the following:

PAPER

TAIL PIPE

Oil Burning • Low oil level • Clogged PCV valve or system, causing blowby and oil to be blown into the air cleaner • Clogged drainback passages in the cylinder head • Dirty oil that has not been changed for a long time (Change the oil and drive for about 1,000 miles, or 1,600 km, and change the oil and filter again.)

FIGURE 26–9 The paper test involves holding a piece of paper near the tailpipe of an idling engine. A good engine should produce even, outward puffs of exhaust. If the paper is sucked in toward the tailpipe, a burned valve is a possibility. TECH TIP

Noises The Paper Test

• Carbon on top of the piston(s) can sound like a bad rod bearing (often called a carbon knock) • Loose torque-to-flex plate bolts (or nuts), causing a loud knocking noise

A soundly running engine should produce even and steady exhaust at the tailpipe. You can test this with the paper test. Hold a piece of paper or a 3˝ ⫻ 5˝ index card (even a dollar bill works) within 1 in. (25 mm) of the tailpipe with the engine running at idle. SEE FIGURE 26–9. The paper should blow out evenly without “puffing.” If the paper is drawn toward the tailpipe at times, the exhaust valves in one or more cylinders could be burned. Other reasons why the paper might be sucked toward the tailpipe include the following:

NOTE: Often this problem will cause noise only at idle; the noise tends to disappear during driving or when the engine is under load. • A loose and/or defective drive belt, which may cause a rod- or main-bearing knocking noise (A loose or broken mount for the generator [alternator], power steering pump, or air-conditioning compressor can also cause a knocking noise.)

STEP 3

1. The engine could be misfiring because of a lean condition that could occur normally when the engine is cold. 2. Pulsing of the paper toward the tailpipe could also be caused by a hole in the exhaust system. If exhaust escapes through a hole in the exhaust system, air could be drawn in during the intervals between the exhaust puffs from the tailpipe to the hole in the exhaust, causing the paper to be drawn toward the tailpipe. 3. Ignition fault causing misfire.

OIL PRESSURE WARNING LAMP The red oil pressure warning lamp in the dash usually lights when the oil pressure is less than 4 to 7 PSI, depending on vehicle and engine. The oil light should not be on during driving. If the oil warning lamp is on, stop the engine immediately. Always confirm oil pressure with a reliable mechanical gauge before performing engine repairs. The sending unit or circuit may be defective.

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An engine compression test is one of the fundamental engine diagnostic tests that can be performed. For smooth engine operation, all cylinders must have equal compression. An engine can lose compression by leakage of air through one or more of only three routes.

Intake or exhaust valve

Piston rings (or piston, if there is a hole)

Cylinder head gasket

For best results, the engine should be warmed to normal operating temperature before testing. An accurate compression test should be performed as follows: STEP 1

Remove all spark plugs. This allows the engine to be cranked to an even speed. Be sure to label all spark plug wires.

FIGURE 26–10 A two-piece compression gauge set. The threaded hose is screwed into the spark plug hole after removing the spark plug. The gauge part is then snapped onto the end of the hose.

CAUTION: Disable the ignition system by disconnecting the primary leads from the ignition coil or module or by grounding the coil wire after removing it from the center of the distributor cap. Also disable the fuel-injection system to prevent the squirting of fuel into the cylinder. STEP 2

STEP 3

Block open the throttle. This permits the maximum amount of air to be drawn into the engine. This step also ensures consistent compression test results. Thread a compression gauge into one spark plug hole and crank the engine. SEE FIGURE 26–10. Continue cranking the engine through four compression strokes. Each compression stroke makes a puffing sound. NOTE: Note the reading on the compression gauge after the first puff. This reading should be at least one-half the final reading. For example, if the final, highest reading is 150 PSI, then the reading after the first puff should be higher than 75 PSI. A low first-puff reading indicates possible weak piston rings. Release the pressure on the gauge and repeat for the other cylinders.

STEP 4

Record the highest readings and compare the results. Most vehicle manufacturers specify the minimum compression reading and the maximum allowable variation among cylinders. Most manufacturers specify a maximum difference of 20% between the highest reading and the lowest reading. For example: If the high reading is Subtract 20% Lowest allowable compression is

150 PSI ⫺30 PSI 120 PSI

NOTE: To make the math quick and easy, think of 10% of 150, which is 15 (move the decimal point to the left one place). Now double it: 15 ⫻ 2 ⫽ 30. This represents 20%. NOTE: During cranking, the oil pump cannot maintain normal oil pressure. Extended engine cranking, such as that which occurs during a compression test, can cause hydraulic lifters to collapse. When the engine starts, loud valve clicking noises may be heard. This should be considered normal after performing a compression test, and the noise should stop after the vehicle has been driven a short distance.

SPARK PLUG

RUBBER HOSE

FIGURE 26–11 Use a vacuum or fuel line hose over the spark plug to install it without danger of cross-threading the cylinder head.

TECH TIP The Hose Trick Installing spark plugs can be made easier by using a rubber hose on the end of the spark plug. The hose can be a vacuum hose, fuel line, or even an old spark plug wire end. SEE FIGURE 26–11. The hose makes it easy to start the threads of the spark plug into the cylinder head. After starting the threads, continue to thread the spark plug for several turns. Using the hose eliminates the chance of crossthreading the plug. This is especially important when installing spark plugs in aluminum cylinder heads.

WET COMPRESSION TEST If the compression test reading indicates low compression on one or more cylinders, add three squirts of oil to the cylinder and retest. This is called a wet compression test, when oil is used to help seal around the piston rings. CAUTION: Do not use more oil than three squirts from a hand-operated oil squirt can. Too much oil can cause a hydrostatic lock, which can damage or break pistons or connecting rods or even crack a cylinder head. Perform the compression test again and observe the results. If the first-puff readings greatly improve and the readings are much higher than without the oil, the cause of the low compression is worn or defective piston rings. If the compression readings increase only slightly (or not at all), then the cause of the low compression is usually defective valves. SEE FIGURE 26–12. NOTE: During both the dry and wet compression tests, be sure that the battery and starting system are capable of cranking the engine at normal cranking speed.

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FIGURE 26–13 A typical handheld cylinder leakage tester. FIGURE 26–12 Badly burned exhaust valve. A compression test could have detected a problem, and a cylinder leakage test (leak-down test) could have been used to determine the exact problem.

RUNNING (DYNAMIC) COMPRESSION TEST A compression test is commonly used to help determine engine condition and is usually performed with the engine cranking. What is the RPM of a cranking engine? An engine idles at about 600 to 900 RPM, and the starter motor obviously cannot crank the engine as fast as the engine idles. Most manufacturers’ specifications require the engine to crank at 80 to 250 cranking RPM. Therefore, a check of the engine’s compression at cranking speed determines the condition of an engine that does not run at such low speeds. But what should be the compression of a running engine? Some would think that the compression would be substantially higher, because the valve overlap of the cam is more effective at higher engine speeds, which would tend to increase the compression. A running compression test, also called a dynamic compression test, is done with the engine running rather than during engine cranking as is done in a regular compression test. Actually, the compression pressure of a running engine is much lower than cranking compression pressure. This results from the volumetric efficiency. The engine is revolving faster, and therefore, there is less time for air to enter the combustion chamber. With less air to compress, the compression pressure is lower. Typically, the higher the engine RPM, the lower the running compression. For most engines, the value ranges are as follows:

Compression during cranking:

125 to 160 PSI

Compression at idle:

60 to 90 PSI

Compression at 2,000 RPM:

30 to 60 PSI

As with cranking compression, the running compression of all cylinders should be equal. Therefore, a problem is not likely to be detected by single compression values, but by variations in running compression values among the cylinders. Broken valve springs, worn valve guides, bent pushrods, and worn cam lobes are some items that would be indicated by a low running compression test reading on one or more cylinders.

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FIGURE 26–14 A whistle stop used to find top dead center. Remove the spark plug and install the whistle stop, then rotate the engine by hand. When the whistle stops making a sound, the piston is at the top.

PERFORMING A RUNNING COMPRESSION TEST

To perform a running compression test, remove just one spark plug at a time. With one spark plug removed from the engine, use a jumper wire to ground the spark plug wire to a good engine ground. This prevents possible ignition coil damage. Start the engine, push the pressure release on the gauge, and read the compression. Increase the engine speed to about 2,000 RPM and push the pressure release on the gauge again. Read the gauge. Stop the engine, reinstall the spark plug, reattach the spark plug wire, and repeat the test for each of the remaining cylinders. Just like the cranking compression test, the running compression test can inform a technician of the relative compression of all the cylinders.

CYLINDER LEAKAGE TEST One of the best tests that can be used to determine engine condition is the cylinder leakage test. This test involves injecting air under pressure into the cylinders one at a time. The amount and location of any escaping air helps the technician determine the condition of the engine. The air is injected into the cylinder through a cylinder leakage gauge into the spark plug hole. SEE FIGURE 26–13. To perform the cylinder leakage test, take the following steps: STEP 1

For best results, the engine should be at normal operating temperature (upper radiator hose hot and pressurized).

STEP 2

The cylinder being tested must be at top dead center (TDC) of the compression stroke. SEE FIGURE 26–14.

NOTE: The greatest amount of wear occurs at the top of the cylinder because of the heat generated near the top of the cylinders. The piston ring flex also adds to the wear at the top of the cylinder. STEP 3

Calibrate the cylinder leakage unit as per manufacturer’s instructions.

STEP 4

Inject air into the cylinders one at a time, rotating the engine as necessitated by firing order to test each cylinder at TDC on the compression stroke.

STEP 5

Evaluate the results: Less than 10% leakage: good Less than 20% leakage: acceptable Less than 30% leakage: poor More than 30% leakage: definite problem NOTE: If leakage seems unacceptably high, repeat the test, being certain that it is being performed correctly and that the cylinder being tested is at TDC on the compression stroke.

STEP 6

Check the source of air leakage. a. If air is heard escaping from the oil filler cap, the piston rings are worn or broken. b. If air is observed bubbling out of the radiator, there is a possible blown head gasket or cracked cylinder head. c. If air is heard coming from the throttle body or air inlet on fuel-injection-equipped engines, there is a defective intake valve(s). d. If air is heard coming from the tailpipe, there is a defective exhaust valve(s).

CYLINDER POWER BALANCE TEST Most large engine analyzers and scan tools have a cylinder power balance feature. The purpose of a cylinder power balance test is to determine if all cylinders are contributing power equally. It determines this by shorting out one cylinder at a time. If the engine speed (RPM) does not drop as much for one cylinder as for other cylinders of the same engine, then the shorted cylinder must be weaker than the other cylinders. For example: Cylinder Number

SPARK PLUG WIRE

TEST LIGHT

3" PIECE OF HOSE

FIGURE 26–15 Using a vacuum hose and a test light to ground one cylinder at a time on a distributorless ignition system. This works on all types of ignition systems and provides a method for grounding out one cylinder at a time without fear of damaging any component. To avoid possible damage to the catalytic converter, do not short out a cylinder for longer than five seconds.

POWER BALANCE TEST PROCEDURE When point-type ignition was used on all vehicles, the common method for determining which, if any, cylinder was weak was to remove a spark plug wire from one spark plug at a time while watching a tachometer and a vacuum gauge. This method is not recommended on any vehicle with any type of electronic ignition. If any of the spark plug wires are removed from a spark plug with the engine running, the ignition coil tries to supply increasing levels of voltage attempting to jump the increasing gap as the plug wires are removed. This high voltage could easily track the ignition coil, damage the ignition module, or both. The acceptable method of canceling cylinders, which will work on all types of ignition systems, including distributorless, is to ground the secondary current for each cylinder. SEE FIGURE 26–15. The cylinder with the least RPM drop is the cylinder not producing its share of power.

RPM Drop When Ignition Is Shorted

1

75

2

70

3

15

4

65

5

75

6

70

Cylinder 3 is the weak cylinder. NOTE: Most automotive test equipment uses automatic means for testing cylinder balance. Be certain to correctly identify the offending cylinder. Cylinder 3 as identified by the equipment may be the third cylinder in the firing order instead of the actual cylinder 3.

VACUUM TESTS Vacuum is pressure below atmospheric pressure and is measured in inches (or millimeters) of mercury (Hg). An engine in good mechanical condition will run with high manifold vacuum. Manifold vacuum is developed by the pistons as they move down on the intake stroke to draw the charge from the throttle body and intake manifold. Air to refill the manifold comes past the throttle plate into the manifold. Vacuum will increase anytime the engine turns faster or has better cylinder sealing while the throttle plate remains in a fixed position. Manifold vacuum will decrease when the engine turns more slowly or when the cylinders no longer do an efficient job of pumping.

FIGURE 26–16 An engine in good mechanical condition should produce 17 to 21 in. Hg of vacuum at idle at sea level.

20

Vacuum in Hg

0 5

30

Pressure P.S.I.

10

Vacuum tests include testing the engine for cranking vacuum, idle vacuum, and vacuum at 2,500 RPM.

CRANKING VACUUM TEST

Measuring the amount of manifold vacuum during cranking is a quick and easy test to determine if the piston rings and valves are properly sealing. (For accurate results, the engine should be warm and the throttle closed.) To perform the cranking vacuum test, take the following steps. STEP 1

Disable the ignition or fuel injection.

STEP 2

Connect the vacuum gauge to a manifold vacuum source.

STEP 3

Crank the engine while observing the vacuum gauge.

Cranking vacuum should be higher than 2.5 in. Hg. (Normal cranking vacuum is 3 to 6 in. Hg.) If it is lower than 2.5 in. Hg, then the following could be the cause.

Too slow a cranking speed

Worn piston rings

Leaking valves

Excessive amounts of air bypassing the throttle plate (This could give a false low vacuum reading. Common sources include a throttle plate partially open or a high-performance camshaft with excessive overlap.)

IDLE VACUUM TEST

An engine in proper condition should idle with a steady vacuum between 17 and 21 in. Hg. SEE FIGURE 26–16.

NOTE: Engine vacuum readings vary with altitude. A reduction of 1 in. Hg per 1,000 ft (300 m) of altitude should be subtracted from the expected values if testing a vehicle above 1,000 ft (300 m).

LOW AND STEADY VACUUM

If the vacuum is lower than normal, yet the gauge reading is steady, the most common causes include:

FIGURE 26–18 A gauge reading with the needle fluctuating 3 to 9 in. Hg below normal often indicates a vacuum leak in the intake system.

10 20

Vacuum in Hg

30

0 5 Pressure P.S.I.

10

FIGURE 26–19 A leaking head gasket can cause the needle to vibrate as it moves through a range from below to above normal.

FLUCTUATING VACUUM

If the needle drops, then returns to a normal reading, then drops again, and again returns, this indicates a sticking valve. A common cause of sticking valves is lack of lubrication of the valve stems. SEE FIGURES 26–18 THROUGH 26–26. If the vacuum gauge fluctuates above and below a center point, burned valves or weak valve springs may be indicated. If the fluctuation is slow and steady, unequal fuel mixture could be the cause. NOTE: A common trick that some technicians use is to squirt some automatic transmission fluid (ATF) down the throttle body or into the air inlet of a warm engine. Often the idle quality improves and normal vacuum gauge readings are restored. The use of ATF does create excessive exhaust smoke for a short time, but it should not harm oxygen sensors or catalytic converters.

FIGURE 26–26 A needle that drops to near zero when the engine is accelerated rapidly and then rises slightly to a reading below normal indicates an exhaust restriction.

EXHAUST RESTRICTION TEST

0 5 Pressure P.S.I.

10

If the exhaust system is restricted, the engine will be low on power, yet smooth. Common causes of restricted exhaust include the following:

FIGURE 26–23 Weak valve springs will produce a normal reading at idle, but as engine speed increases, the needle will fluctuate rapidly between 12 and 24 in. Hg.

Clogged catalytic converter. Always check the ignition and fuel-injection systems for faults that could cause excessive amounts of unburned fuel to be exhausted. Excessive unburned fuel can overheat the catalytic converter and cause the beads or structure of the converter to fuse together, creating the restriction. A defective fuel delivery system could also cause excessive unburned fuel to be dumped into the converter.

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Clogged or restricted muffler. This can cause low power. Often a defective catalytic converter will shed particles that can clog a muffler. Broken internal baffles can also restrict exhaust flow.

Damaged or defective piping. This can reduce the power of any engine. Some exhaust pipe is constructed with double walls, and the inside pipe can collapse and form a restriction that is not visible on the outside of the exhaust pipe.

TESTING BACK PRESSURE WITH A VACUUM GAUGE

FIGURE 26–27 A technician-made adapter used to test exhaust system back pressure.

A vacuum gauge can be used to measure manifold vacuum at a high idle (2000 to 2500 RPM). If the exhaust system is restricted, pressure increases in the exhaust system. This pressure is called back pressure. Manifold vacuum will drop gradually if the engine is kept at a constant speed if the exhaust is restricted. The reason the vacuum will drop is that all exhaust leaving the engine at the higher engine speed cannot get through the restriction. After a short time (within one minute), the exhaust tends to “pile up” above the restriction and eventually remains in the cylinder of the engine at the end of the exhaust stroke. Therefore, at the beginning of the intake stroke, when the piston traveling downward should be lowering the pressure (raising the vacuum) in the intake manifold, the extra exhaust in the cylinder lowers the normal vacuum. If the exhaust restriction is severe enough, the vehicle can become undriveable because cylinder filling cannot occur except at idle.

TESTING BACK PRESSURE WITH A PRESSURE GAUGE

With an oxygen sensor. Use a back pressure gauge and adapter or remove the inside of an old, discarded oxygen sensor and thread in an adapter to convert to a vacuum or pressure gauge.

With the exhaust gas recirculation (EGR) valve. Remove the EGR valve and fabricate a plate to connect to a pressure gauge. NOTE: An adapter can be easily made by inserting a metal tube or pipe. A short section of brake line works great. The pipe can be brazed to the oxygen sensor housing or it can be glued in with epoxy. An 18 mm compression gauge adapter can also be adapted to fit into the oxygen sensor opening. SEE FIGURE 26–27.

With the air-injection reaction (AIR) check valve. Remove the check valve from the exhaust tubes leading down to the exhaust manifold. Use a rubber cone with a tube inside to seal against the exhaust tube. Connect the tube to a pressure gauge. Exhaust system back pressure can be measured directly by installing a pressure gauge into an exhaust opening. This can be accomplished in one of the following ways.

At idle, the maximum back pressure should be less than 1.5 PSI (10 kPa), and it should be less than 2.5 PSI (15 kPa) at 2500 RPM.

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FIGURE 26–28 A tester that uses a blue liquid to check for exhaust gases in the exhaust, which would indicate a head gasket leak problem.

DIAGNOSING HEAD GASKET FAILURE Several items can be used to help diagnose a head gasket failure.

Exhaust gas analyzer. With the radiator cap removed, place the probe from the exhaust analyzer above the radiator filler neck. If the HC reading increases, the exhaust (unburned hydrocarbons) is getting into the coolant from the combustion chamber.

Chemical test. A chemical tester using blue liquid is also available. The liquid turns yellow if combustion gases are present in the coolant. SEE FIGURE 26–28.

Bubbles in the coolant. Remove the coolant pump belt to prevent pump operation. Remove the radiator cap and start the engine. If bubbles appear in the coolant before it begins to boil, a defective head gasket or cracked cylinder head is indicated.

Excessive exhaust steam. If excessive water or steam is observed coming from the tailpipe, this means that coolant is getting into the combustion chamber from a defective head gasket or a cracked head. If there is leakage between cylinders, the engine usually misfires and a power balancer test and/or compression test can be used to confirm the problem.

If any of the preceding indicators of head gasket failure occur, remove the cylinder head(s) and check all of the following: 1. Head gasket 2. Sealing surfaces—for warpage 3. Castings—for cracks NOTE: A leaking thermal vacuum valve can cause symptoms similar to those of a defective head gasket. Most thermal vacuum valves thread into a coolant passage, and they often leak only after they get hot.

COOLANT TEMPERATURE LIGHT

Most vehicles are equipped with a coolant temperature gauge or dash warning light. The warning light may be labeled “coolant,” “hot,” or “temperature.” If the coolant temperature warning light comes on during driving, this usually indicates that the coolant temperature is above a safe level, or above about 250°F (120°C). Normal coolant temperature should be about 200°F to 220°F (90°C to 105°C). If the coolant temperature light comes on during driving, the following steps should be followed to prevent possible engine damage. 1. Turn off the air conditioning and turn on the heater. The heater will help get rid of some of the heat in the cooling system.

DASH WARNING LIGHTS Most vehicles are equipped with several dash warning lights often called “telltale” or “idiot” lights. These lights are often the only warning a driver receives that there may be engine problems. A summary of typical dash warning lights and their meanings follows.

OIL (ENGINE) LIGHT The red oil light indicates that the engine oil pressure is too low (usually lights when oil pressure is 4 to 7 PSI [20 to 50 kPa]). Normal oil pressure should be 10 to 60 PSI (70 to 400 kPa) or 10 PSI per 1000 engine RPM. When this light comes on, the driver should shut off the engine immediately and check the oil level and condition for possible dilution with gasoline caused by a fuel system fault. If the oil level is okay, then there is a possible serious engine problem or a possible defective oil pressure sending (sender) unit. The automotive technician should always check the oil pressure using a reliable mechanical oil pressure gauge if low oil pressure is suspected.

2. Raise the engine speed in neutral or park to increase the circulation of coolant through the radiator. 3. If possible, turn the engine off and allow it to cool (this may take over an hour). 4. Do not continue driving with the coolant temperature light on (or the gauge reading in the red warning section or above 260°F) or serious engine damage may result. NOTE: If the engine does not feel or smell hot, it is possible that the problem is a faulty coolant temperature sensor or gauge.

TECH TIP Misfire Diagnosis If a misfire goes away with propane added to the air inlet, suspect a lean injector.

NOTE: Some automobile manufacturers combine the dash warning lights for oil pressure and coolant temperature into one light, usually labeled “engine.” Therefore, when the engine light comes on, the technician should check for possible coolant temperature and/or oil pressure problems.

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COMPRESSION TEST

1

The tools and equipment needed to perform a compression test include a compression gauge, an air nozzle, and the socket ratchets and extensions that may be necessary to remove the spark plugs from the engine.

3

Block open the throttle (and choke, if the engine is equipped with a carburetor). Here a screwdriver is being used to wedge the throttle linkage open. Keeping the throttle open ensures that enough air will be drawn into the engine so that the compression test results will be accurate.

5

Remove all of the spark plugs. Be sure to mark the spark plug wires so that they can be reinstalled onto the correct spark plugs after the compression test has been performed.

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2

To prevent ignition and fuel-injection operation while the engine is being cranked, remove both the fuelinjection fuse and the ignition fuse. If the fuses cannot be removed, disconnect the wiring connectors for the injectors and the ignition system.

4

Before removing the spark plugs, use an air nozzle to blow away any dirt that may be around the spark plug. This step helps prevent debris from getting into the engine when the spark plugs are removed.

6

Select the proper adapter for the compression gauge. The threads on the adapter should match those on the spark plug.

STEP BY STEP

7

If necessary, connect a battery charger to the battery before starting the compression test. It is important that consistent cranking speed be available for each cylinder being tested.

9

After the engine has been cranked for four “puffs,” stop cranking the engine and observe the compression gauge.

11

If a cylinder(s) is lower than most of the others, use an oil can and squirt two squirts of engine oil into the cylinder and repeat the compression test. This is called performing a wet compression test.

8

Make a note of the reading on the gauge after the first “puff,” which indicates the first compression stroke that occurred on that cylinder as the engine was being rotated. If the first puff reading is low and the reading gradually increases with each puff, weak or worn piston rings may be indicated.

10

12

Record the first puff and this final reading for each cylinder. The final readings should all be within 20% of each other.

If the gauge reading is now much higher than the first test results, then the cause of the low compression is due to worn or defective piston rings. The oil in the cylinder temporarily seals the rings which causes the higher reading.

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REVIEW QUESTIONS 1. Describe the visual checks that should be performed on an engine if a mechanical malfunction is suspected. 2. List three simple items that could cause excessive oil consumption. 3. List three simple items that could cause engine noises. 4. Describe how to perform a compression test and how to determine what is wrong with an engine based on a compression test result.

5. Describe the cylinder leakage test. 6. Describe how a vacuum gauge would indicate if the valves were sticking in their guides. 7. Describe the test procedure for determining if the exhaust system is restricted (clogged) using a vacuum gauge.

CHAPTER QUIZ 1. Technician A says that the paper test could detect a burned valve. Technician B says that a grayish white stain on the engine could be a coolant leak. Which technician is correct? a. Technician A only c. Both Technicians A and B b. Technician B only d. Neither Technician A nor B 2. Two technicians are discussing oil leaks. Technician A says that an oil leak can be found using a fluorescent dye in the oil with a black light to check for leaks. Technician B says that a white spray powder can be used to locate oil leaks. Which technician is correct? a. Technician A only c. Both Technicians A and B b. Technician B only d. Neither Technician A nor B 3. Which of the following is the least likely to cause an engine noise? a. Carbon on the pistons b. Cracked exhaust manifold c. Loose accessory drive belt d. Vacuum leak 4. A good engine should produce how much compression during a running (dynamic) compression test at idle? a. 150 to 200 PSI c. 60 to 90 PSI b. 100 to 150 PSI d. 30 to 60 PSI 5. A smoothly operating engine depends on ______________. a. High compression on most cylinders b. Equal compression between cylinders c. Cylinder compression levels above 100 PSI (700 kPa) and within 70 PSI (500 kPa) of each other d. Compression levels below 100 PSI (700 kPa) on most cylinders

chapter

27

6. A good reading for a cylinder leakage test would be ______________. a. Within 20% between cylinders b. All cylinders below 20% leakage c. All cylinders above 20% leakage d. All cylinders above 70% leakage and within 7% of each other 7. Technician A says that during a power balance test, the cylinder that causes the biggest RPM drop is the weak cylinder. Technician B says that if one spark plug wire is grounded out and the engine speed does not drop, a weak or dead cylinder is indicated. Which technician is correct? a. Technician A only c. Both Technicians A and B b. Technician B only d. Neither Technician A nor B 8. Cranking vacuum should be ______________. a. 2.5 in. Hg or higher c. 17 to 21 in. Hg b. Over 25 in. Hg d. 6 to 16 in. Hg 9. Technician A says that a leaking head gasket can be tested for using a chemical tester. Technician B says that leaking head gasket can be found using an exhaust gas analyzer. a. Technician A only c. Both Technicians A and B b. Technician B only d. Neither Technician A nor B 10. The low oil pressure warning light usually comes on ______________. a. Whenever an oil change is required b. Whenever oil pressure drops dangerously low (4 to 7 PSI) c. Whenever the oil filter bypass valve opens d. Whenever the oil filter antidrainback valve opens

FIGURE 27–1 If the thermostat has a jiggle valve, it should be placed toward the top to allow air to escape. If a thermostat were to become stuck open or open too soon, this can set a diagnostic trouble code P0128 (coolant temperature below thermostat regulating temperature).

FIGURE 27–2 Use caution if using a steel scraper to remove a gasket from aluminum parts. It is best to use a wood or plastic scraper.

STEP 6

Refill the cooling system with the specified coolant and bleed any trapped air from the system.

STEP 7

Pressurize the cooling system to verify that there are no leaks around the thermostat housing.

STEP 8

Run the engine until it reaches normal operating temperature and check for leaks.

STEP 9

Verify that the engine is reaching correct operating temperature.

THERMOSTAT REPLACEMENT FAILURE PATTERNS All thermostat valves move during operation to maintain the desired coolant temperature. Thermostats can fail in the following ways.

Stuck open. If a thermostat fails open or partially open, the operating temperature of the engine will be less than normal. SEE FIGURE 27–1.

Stuck closed. If the thermostat fails closed or almost closed, the engine will likely overheat.

Stuck partially open. This will cause the engine to warm up slowly if at all. This condition can cause the powertrain control module (PCM) to set a P0128 diagnostic trouble code (DTC) which means that the engine coolant temperature does not reach the specified temperature.

Skewed. A skewed thermostat works, but not within the correct temperature range. Therefore, the engine could overheat or operate cooler than normal or even do both.

REPLACEMENT PROCEDURE Before replacing the thermostat, double-check that the cooling system problem is not due to another fault, such as being low on coolant or an inoperative cooling fan. Check service information for the specified procedure to follow to replace the thermostat. Most recommended procedures include the following steps. STEP 1

Allow the engine to cool for several hours so the engine and the coolant should be at room temperature.

STEP 2

Drain the coolant into a suitable container. Most vehicle manufacturers recommend that new coolant be used and the old coolant disposed of properly or recycled.

WATER PUMP REPLACEMENT NEED FOR REPLACEMENT

A water pump will require replacement if any of the following conditions are present.

REPLACEMENT GUIDELINES After diagnosis has been confirmed that the water pump requires replacement, check service information for the exact procedure to follow. The steps usually include the following: STEP 1

Allow the engine to cool to room temperature.

STEP 2

Drain the coolant and dispose of properly or recycle.

STEP 3

Remove engine components to gain access to the water pump as specified in service information.

STEP 4

Remove the water pump assembly.

STEP 5

Clean the gasket surfaces and install the new water pump using a new gasket or seal as needed. SEE FIGURE 27–2. Torque all fasteners to factory specifications.

STEP 3

Remove any necessary components to get access to the thermostat.

STEP 4

Remove the thermostat housing and thermostat.

STEP 6

Install removed engine components.

STEP 5

Replace the thermostat housing gasket and thermostat. Torque all fasteners to specifications.

STEP 7

Fill the cooling system with the specified coolant.

STEP 8

Run the engine, check for leaks, and verify proper operation.

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FIGURE 27–3 An intake manifold gasket that failed and allowed coolant to be drawn into the cylinder(s).

INTAKE MANIFOLD GASKET INSPECTION

FIGURE 27–4 The lower intake manifold attaches to the cylinder heads.

CAUSES OF FAILURE Many V-type engines leak oil, coolant, or experience an air (vacuum) leak caused by a leaking intake manifold gasket. This failure can be contributed to one or more of the following: 1. Expansion/contraction rate difference between the cast-iron head and the aluminum intake manifold can cause the intake manifold gasket to be damaged by the relative motion of the head and intake manifold. This type of failure is called fretting. 2. Plastic (Nylon 6.6) gasket deterioration caused by the coolant. SEE FIGURE 27–3.

DIAGNOSIS OF LEAKING INTAKE MANIFOLD GASKET Because intake manifold gaskets are used to seal oil, air, and coolant in most causes, determining that the intake manifold gasket is the root cause can be a challenge. To diagnose a possible leaking intake manifold gasket, perform the following tests. Visual inspection. Check for evidence of oil or coolant between the intake manifold and the cylinder heads. Coolant level. Check the coolant level and determine if the level has been dropping. A leaking intake manifold gasket can cause coolant to leak and then evaporate, leaving no evidence of the leak. Air (vacuum) leak. If there is a stored diagnostic trouble code (DTC) for a lean exhaust (P0171, P0172, or P0174), a leaking intake manifold gasket could be the cause. Use propane to check if the engine changes when dispensed around the intake manifold gasket. If the engine changes in speed or sound, then this test verifies that an air leak is present.

INTAKE MANIFOLD GASKET REPLACEMENT When replacing the intake manifold gasket, always check service information for the exact procedure to follow. The steps usually include the following: STEP 1

254

Be sure the engine has been off for about an hour and then drain the coolant into a suitable container.

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FIGURE 27–5 The upper intake manifold, often called a plenum, attaches to the lower intake manifold. STEP 2

Remove covers and other specified parts needed to get access to the retaining bolts.

STEP 3

To help ensure that the manifold does not warp when removed, loosen all fasteners in the reverse order of the tightening sequence. This means that the bolts should be loosened starting at the ends and working toward the center.

STEP 4

Remove the upper intake manifold (plenum), if equipped, and inspect for faults. SEE FIGURES 27–4 AND 27–5.

STEP 5

Remove the lower intake manifold, using the same bolt removal procedure of starting at the ends and working toward the center.

STEP 6

Thoroughly clean the area and replace the intake manifold if needed. Check that the correct replacement manifold is being used, and even the current part could look different from the original. SEE FIGURE 27–6.

STEP 7

Install the intake manifold using new gaskets as specified. Some designs use gaskets that are reusable. Replace as needed.

STEP 8

Torque all fasteners to factory specifications and in the proper sequences. The tightening sequences usually start at the center and work outward to the ends. CAUTION: Double-check the torque specifications and be sure to use the correct values. Many intake manifolds use fasteners that are torqued to values expressed in pound-inches and not pound-feet.

FIGURE 27–6 Many aftermarket replacement intake manifolds have a different appearance from the original manifold. STEP 9

Reinstall all parts needed to allow the engine to start and run, including refilling the coolant if needed.

STEP 10 Start the engine and check for leaks and proper engine operation. STEP 11 Reset or relearn the idle if specified, using a scan tool.

FIGURE 27–7 A single overhead camshaft engine with a timing belt that also rotates the water pump.

STEP 12 Install all of the remaining parts and perform a test drive to verify proper operation and no leaks.

Check (verify) that the camshaft timing is correct by rotating the engine several revolutions.

STEP 7

Install enough components to allow the engine to start to verify proper operation. Check for any leaks, especially if seals have been replaced.

STEP 8

Complete the reassembly of the engine and perform a test drive before returning the vehicle to the customer.

STEP 13 Check and replace the air filter if needed. STEP 14 Change the engine oil if the intake manifold leak could have caused coolant to leak into the engine, which would contaminate the oil.

TIMING BELT REPLACEMENT NEED FOR REPLACEMENT

Timing belts have a limited service and a specified replacement interval ranging from 60,000 miles (97,000 km) to about 100,000 miles (161,000 km). Timing belts are required to be replaced if any of the following conditions occur.

Before replacing the timing belt, check service information for the recommended procedure to follow. Most timing belt replacement procedures include the following steps. STEP 1

Allow the engine to cool before starting to remove components to help eliminate the possibility of personal injury or warpage of the parts.

STEP 2

Remove all necessary components to gain access to the timing belt and timing marks.

STEP 3

STEP 4

If the timing belt is not broken, rotate the engine until the camshaft and crankshaft timing marks are aligned according to the specified marks. SEE FIGURE 27–7. Loosen or remove the tensioner as needed to remove the timing belt.

HYBRID ENGINE PRECAUTIONS HYBRID VEHICLE ENGINE OPERATION

Gasoline engines used in hybrid electric vehicles (HEVs) and in extended range electric vehicles (EREVs) can be a hazard to be around under some conditions. These vehicles are designed to stop the gasoline engines unless needed. This feature is called idle stop. This means that the engine is not running, but could start at any time if the computer detects the need to charge the hybrid batteries or other issue that requires the gasoline engine to start and run.

PRECAUTIONS Always check service information for the exact procedures to follow when working around or under the hood of a hybrid electric vehicle. These precautions could include:

Before working under the hood or around the engine, be sure that the ignition is off and the key is out of the ignition. Check that the “Ready” light is off. SEE FIGURE 27–8.

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FIGURE 27–8 A Toyota/Lexus hybrid electric vehicle has a ready light. If the ready light is on, the engine can start at anytime without warning.

Do not touch any circuits that have orange electrical wires or conduit. The orange color indicates dangerous high-voltage wires, which could cause serious injury or death if touched. Always use high-voltage linesman’s gloves whenever depowering the high-voltage system.

HYBRID ENGINE SERVICE

The gasoline engine in most hybrid electric vehicles specifies low viscosity engine oil as a way to achieve maximum fuel economy. SEE FIGURE 27–9. The viscosity required is often:

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FIGURE 27–9 Always use the viscosity of oil as specified on the oil fill cap.

SAE 0W-20

SAE 5W-20

Many shops do not keep this viscosity in stock so preparations need to be made to get and use the specified engine oil. In addition to engine oil, some hybrid electric vehicles such as the Honda Insight (1999–2004) require special spark plugs. Check service information for the specified service procedures and parts needed if a hybrid electric vehicle is being serviced.

VALVE ADJUSTMENT

1

Before starting the process of adjusting the valves, look up the specifications and exact procedures. The technician is checking this information from a computer CD-ROM-based information system.

2

The tools necessary to adjust the valves on an engine with adjustable rocker arms include basic hand tools, feeler gauge, and a torque wrench.

3

An overall view of the 4-cylinder engine that is due for a scheduled valve adjustment according to the vehicle manufacturer’s recommendations.

4

Start the valve adjustment procedure by first disconnecting and labeling, if necessary, all vacuum lines that need to be removed to gain access to the valve cover.

5

The air intake tube is being removed from the throttle body.

6

With all vacuum lines and the intake tube removed, the valve cover can be removed after removing all retaining bolts.

CONTINUED

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VALVE ADJUSTMENT

7

(CONTINUED)

Notice how clean the engine appears. This is a testament of proper maintenance and regular oil changes by the owner.

8

To help locate how far the engine is being rotated, the technician is removing the distributor cap to be able to observe the position of the rotor.

TIMING PLATE WITH DEGREES

9

The engine is rotated until the timing marks on the front of the crankshaft line up with zero degrees—top dead center (TDC)—with both valves closed on #1 cylinder.

11 258

If the valve clearance (lash) is not correct, loosen the retaining nut and turn the valve adjusting screw with a screwdriver to achieve the proper clearance.

CHAPTER 2 7

10

With the rocker arms contacting the base circle of the cam, insert a feeler gauge of the specified thickness between the camshaft and the rocker arm. There should be a slight drag on the feeler gauge.

12

After adjusting the valves that are closed, rotate the engine one full rotation until the engine timing marks again align.

STEP BY STEP

13

The engine is rotated until the timing marks again align indicating that the companion cylinder will now be in position for valve clearance measurement.

14

On some engines, it is necessary to watch the direction the rotor is pointing to help determine how far to rotate the engine. Always follow the vehicle manufacturer’s recommended procedure.

15

The technician is using a feeler gauge that is one-thousandth of an inch thinner and another onethousandth of an inch thicker than the specified clearance as a double-check that the clearance is correct.

16

Adjusting a valve takes both hands—one to hold the wrench to loosen and tighten the lock nut and one to turn the adjusting screw. Always double check the clearance after an adjustment is made.

17

After all valves have been properly measured and adjusted as necessary, start the reassembly process by replacing all gaskets and seals as specified by the vehicle manufacturer.

18

Reinstall the valve cover being careful to not pinch a wire or vacuum hose between the cover and the cylinder head.

CONTINUED

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VALVE ADJUSTMENT

(CONTINUED)

19

Use a torque wrench and torque the valve cover retaining bolts to factory specifications.

20

Reinstall the distributor cap.

21

Reinstall the spark plug wires and all brackets that were removed to gain access to the valve cover.

22

Reconnect all vacuum and air hoses and tubes. Replace any vacuum hoses that are brittle or swollen with new ones.

23

Be sure that the clips are properly installed. Start the engine and check for proper operation.

24

Double-check for any oil or vacuum leaks after starting the engine.

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REVIEW QUESTIONS 1. How can a thermostat fail?

4. Why must timing belts be replaced?

2. How can a water pump fail requiring replacement?

5. Why is it important that the READY light be out on the dash before working under the hood of a hybrid electric vehicle?

3. What will happen to the engine if the intake manifold gasket fails?

CHAPTER QUIZ 1. A thermostat can fail in which way? a. Stuck open b. Stuck closed c. Stuck partially open d. Any of the above 2. A skewed thermostat means it is ______________. a. Working, but not at the correct temperature b. Not working c. Missing the thermo wax in the heat sensor d. Contaminated with coolant

6. A defective thermostat can cause the powertrain control module to set what diagnostic trouble code (DTC)? a. P0171 b. P0172 c. P0128 d. P0300 7. A replacement plastic intake manifold may have a different design or appearance from the original factory-installed part. a. True b. False

3. Coolant drained from the cooling system when replacing a thermostat or water pump should be ______________. a. Reused b. Disposed of properly or recycled c. Filtered and reinstalled after the repair d. Poured down a toilet

8. The torque specifications for many plastic intake manifolds are in what unit? a. Pound-inches b. Pound-feet c. Ft-lb per minute d. Lb-ft per second

4. A water pump can fail to provide the proper amount of flow of coolant through the cooling system if what has happened? a. The coolant is leaking from the weep hole. b. The bearing is noisy. c. The impeller blades are worn or slipping on the shaft. d. A bearing failure has caused the shaft to become loose.

9. When replacing a timing belt, many experts and vehicle manufacturers recommend that what other part(s) should be replaced? a. Tensioner assembly b. Water pump c. Camshaft oil seal(s) d. All of the above

5. Intake manifold gaskets on a V-type engine can fail due to what factor? a. Fretting b. Coolant damage c. Relative movement between the intake manifold and the cylinder head d. All of the above

OBJECTIVES: After studying Chapter 28, the reader should be able to: • Prepare for ASE Engine Repair (A1) certification test content areas “B” (Cylinder Head and Valve Train Diagnosis and Repair) and “C” (Engine Block Diagnosis and Repair). • Explain the differences between a long block and a short block assembly. • Describe how to remove an engine from a vehicle. • Explain how to remove engine accessory components, such as the covers and valve train components. • Discuss how to remove cylinder heads without causing warpage. • List the steps necessary to remove a piston from a cylinder. • Explain how to remove a valve from a cylinder head. KEY TERMS: Freshening 262 • Long block 262 • Rebuilding 262 • Short block 262 • Vibration damper 267

FIGURE 28–2 A crate engine from Chrysler to be used in a restored muscle car. Using a complete new engine costs more than rebuilding an existing engine, but it has a warranty and uses all new parts.

ENGINE REPAIR OPTIONS TECHNICIAN AND OWNER DECISION The decision to repair an engine should be based on all the information about the engine that is available to the service technician and the vehicle owner.

In some cases, the engine might not be worth repairing. It is the responsibility of the technician to discuss the advantages and disadvantages of the different repair options with the customer.

The customer, who is paying for the repair, must make the final decision on the reconditioning procedure to be used. The repair might involve replacing a worn component instead of reconditioning. The decision will be based on the recommendation of the service technician.

taken out. The customer should be informed about any other engine problem, in order to authorize the service that the engine requires. In the high-performance industry, this procedure is called freshening the engine.

Major overhaul. A complete engine reconditioning job is called rebuilding. Sometimes, this type of reconditioning is called a major overhaul. To rebuild the engine, the engine must be removed from the chassis and be completely disassembled. All serviceable parts are reconditioned to either new or service standards. All bearings, gaskets, and seals are replaced. When the reconditioning is done properly, a rebuilt engine should operate like a new engine.

Short block. The quickest way to get a vehicle back in service is to exchange the faulty engine for a different one. In an older vehicle, the engine may be replaced with a used engine from a salvage yard. In some cases, only a reconditioned block, including the crankshaft, rods, and pistons, is used. This replacement assembly is called a short block. The original heads, valve train, oil pump, and all external components are reconditioned and used on the short block.

Long block. The replacement assembly is called a long block when the reconditioned assembly includes the heads and valve train. Many automotive machine shops maintain a stock of short and long blocks of popular engines. Usually, the original engine parts, called the core, are exchanged for the reconditioned assembly. The core parts are reconditioned by the automotive machine shop and put back in stock for the next customer.

Crate engines. Crate engines are new engines built by the engine manufacturer and sold through vehicle dealers. SEE FIGURE 28–2.

Remanufactured engines. Some engines are remanufactured and can be replaced in a day or two, greatly reducing the amount of time the customer is without a vehicle. The engine cores are completely disassembled, and each serviceable part is reconditioned with specialized machinery. Engines are then assembled on an engine assembly line similar to the original manufacturer’s assembly line. The parts that are assembled together as an engine have not come out of the same engine. The remanufactured engine usually has new pistons, valves, and lifters, together with other parts that are normally replaced in a rebuilt engine. All clearances and fits in the remanufactured

REPAIR OPTIONS

Most customers want to spend the least amount of money possible, so they have only the faulty component repaired. This is the correct procedure in many cases. Examples of component repairs include:

Component replacement. Timing chain replacement is an example of a component repair due to wear that can cause a loss of engine performance. If testing indicates that the timing chain has excessive slack, the front of the engine can be disassembled and the actual slack measured. Usually a slack of 0.5 in. (13 mm) or more indicates that the timing chain and gears need to be replaced. SEE FIGURE 28–1. Valve job. Valve leakage is corrected by doing a valve job. This does not necessarily correct the customer’s concerns, however. Stopping valve leakage improves manifold vacuum. After completing a valve job, the greater manifold vacuum may draw the oil past worn piston rings and into the combustion chamber during the intake stroke, causing oil consumption to increase. Minor overhaul. A minor overhaul can usually be done without removing the engine from the chassis. It requires removal of both the head and the oil pan. The overhaul is usually done when the engine lacks power, has poor fuel economy, uses an excessive amount of oil, produces visible tailpipe emissions, runs rough, or is hard to start. It is still only a repair procedure. Parts normally replaced include the piston rings, rod bearings and gaskets, as well as a valve job. Other engine problems may be noticed after the oil pan is removed and the piston and rod assemblies are

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engine are the same as in a new engine. A remanufactured engine should give service as good as that of a new engine, and it will cost about half as much. Remanufactured engines usually carry a warranty. This means that they will be replaced if they fail during the period of the warranty. They may even cost less than a rebuilt engine, because much of the reconditioning is done by specialized machines rather than by expensive skilled labor.

TECH TIP A Picture Is Worth a Thousand Words Take pictures with a cell phone camera, digital camera, or a video camcorder of the engine being serviced. These pictures will be worth their weight in gold when it comes time to reassemble or reinstall the engine. It is very difficult for anyone to remember the exact location of every bracket, wire, and hose. Referring back to the photos of the engine before work was started will help you restore the vehicle to like-new condition.

ENGINE REMOVAL CHECK SERVICE INFORMATION

Whenever any enginerelated work is being performed, always print out the specified procedure as published in service information to avoid doing any harm to the vehicle or the engine.

USUAL ENGINE REMOVAL PROCEDURES

Drain the engine oil. Draining the engine oil and removing the oil filter also helps prevent fluid loss during the removal process.

Disconnect wiring and vacuum hoses. Mark and remove all vacuum hoses and electrical wiring attached to the engine.

The procedures

that are usually specified include:

Remove the hood. Removing the hood allows easier access to all of the components around the engine. Store the hood in a place where it will not be damaged. Some technicians place a fender cover on the roof of the vehicle and then place the hood upside down on top of the fender cover. Clean the engine area. The engine exterior and the engine compartment should be cleaned before work is begun. Using a power washer is the most commonly used way to clean the engine compartment area. A clean engine is easier to work on, and the cleaning not only helps to keep dirt out of the engine, but also minimizes accidental damage from slipping tools.

Disconnect the negative (⫺) battery cable, and remove the battery from the vehicle if it could interfere with the removal of the engine.

Remove the air cleaner assembly. Remove the hoses and other components of the air intake system. Mark or bag and tag all fasteners.

Remove all accessories. Those that usually need to be removed include the alternator, engine driven fan, and AIR pump, if equipped.

Drain the coolant. Draining coolant from the radiator and the engine block help reduce the chance of coolant getting into the cylinders when the cylinder head is removed. Dispose of the used coolant properly.

Remove the radiator. Disconnect the transmission oil cooler lines and radiator hoses from the radiator. Removing the radiator helps provide room for moving the engine during removal and helps prevent the possibility of damage.

Disconnect the exhaust system. On some engines, it may be easier to remove the exhaust manifold(s) from the cylinder head(s), whereas on others, it may be easier to disconnect the exhaust pipe from the manifold(s).

Recover the air-conditioning refrigerant. Set the airconditioning compressor aside and do not open the system unless absolutely necessary. If the air-conditioning system has to be opened to remove components, then the system must be evacuated. Tape or cover all open refrigerant fittings and hoses to prevent contaminants from entering the A/C system. Check service information for the exact procedures to follow.

Remove the power steering pump. Remove the fasteners to the power steering pump and set aside the pump and hoses.

PROCEDURE FOR ENGINE REMOVAL

There are two ways

to remove the engine. 1. The engine can be lifted out of the chassis with the transmission/transaxle attached. 2. The transmission/transaxle can be separated from the engine and left in the chassis. The method to be used must be determined before the engine is removed from the vehicle.

Rear-wheel-drive vehicle. The removal procedure for most rear-wheel-drive vehicles includes the following steps. STEP 1 Under the vehicle, remove the driveshaft (propeller shaft) and disconnect the exhaust pipes. Also remove the engine (motor) mounts. In some installations, it may be necessary to loosen the steering linkage idler arm to give clearance. The transmission controls and wiring need to be disconnected at the connectors, and clutch linkages disconnected and labeled. STEP 2 Attach a sling, either a chain or lift cable, to one of the following: • Factory-installed lifting hooks • Intake manifold • Cylinder head bolts, on top of the engine An engine lift hoist chain or cable is attached and snugged to take most of the weight. This leaves the engine resting on the mounts. NOTE: For the best results, use the factoryinstalled lifting hooks that are attached to the engine. These hooks are used in the assembly plant to install the engine and are usually in the best location to remove the engine. STEP 3 Remove the rear cross-member, and lower the transmission. Cover the extension housing with a plug or a plastic bag to help prevent the automatic transmission fluid from leaking during the removal process. If the engine alone is being removed, the transmission retaining bolts and torque converter fasteners will need to be removed. Check service information for exact procedures to follow when removing an automatic transmission.

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FIGURE 28–3 An engine must be tipped as it is pulled from the chassis.

RACK AND PINION STEERING GEAR CRADLE

FIGURE 28–5 The entire cradle, which included the engine, transaxle, and steering gear, was removed and placed onto a stand. The rear cylinder head has been removed to check for the root cause of a coolant leak. TECH TIP Tag and Bag

FIGURE 28–4 When removing just the engine from a front-wheeldrive vehicle, the transaxle must be supported. Shown here is a typical fixture that can be used to hold the engine if the transaxle is removed or to hold the transaxle if the engine is removed. STEP 4 The front of the engine must come almost straight up as the transmission slides from under the floor pan. The engine and transmission are hoisted free of the automobile, swung clear, and lowered on an open floor area. SEE FIGURE 28–3.

Front-wheel-drive vehicle. Check service information for the exact procedure to follow to remove the engine from a frontwheel-drive vehicle. Depending on the vehicle, the engine could be removed from the top or lowered and removed from underneath on many front-wheel-drive vehicles. Typical steps include: STEP 1 Disconnect units that might interfere with engine removal, including the steering unit, engine electrical harness, and radiator. STEP 2 If removing the engine from underneath, the upper strut and lower engine cradle fasteners will have to be removed. STEP 3 Disconnect the torque converter and bell housing bolts and clutch linkage if required. STEP 4 Often special holding fixtures are required to help hold the transaxle in place while removing the engine. SEE FIGURES 28–4 AND 28–5.

All components and fasteners should be marked for future reference. Large components should be marked or a tag installed that identifies the part. Smaller parts and fasteners should be placed in plastic bags and labeled as to what they are used for, such as the water pump bolts.

Always use at least four grade 8 bolts when mounting an engine to an engine stand. Using low-quality nongraded bolts or fewer than four bolts can cause the engine to fall. Also check to ensure that the proper threads of bolts are being used. Some engines use fractional threads, whereas others use metric threads.

Install the bolts so that at least 1/2 in. (13 mm) of thread is engaged in the back of the engine to ensure that the fasteners are securely attached the engine block.

Check that the engine is properly balanced on the engine stand before work is started on the engine. SEE FIGURE 28–6.

DISASSEMBLING A CAM-IN-BLOCK (OHV) ENGINE Check service information for the specified engine disassembly procedure. Read, understand, and follow all safety instructions. Following are the usual steps involved. STEP 1

Engines should be cold before disassembly to minimize the chance of warpage of the components that are being removed.

STEP 2

Removal of the rocker arm covers gives the first opportunity to see inside a part of the engine. Examine the rocker arms, valve springs, and valve tips for obvious defects. Remove the rocker arms and pushrods and, if they are to be reused, place them in a location so that the rockers and the pushrods can be installed back to their original location. SEE FIGURE 28–7.

STEP 3

Remove the intake manifold bolts and lift off the manifold. Use care to avoid damaging the parting surface as the gasket is loosened. When the intake manifold and lifter valley cover

ENGINE DISASSEMBLY MOUNTING THE ENGINE ON A STAND Engines should be installed to a sturdy engine stand. For safety, always check the following:

FIGURE 28–8 Sometimes after the cylinder head has been removed, the engine condition is discovered to be so major that the entire engine may need to be replaced rather than overhauled. TECH TIP Disassembly Is the Reverse Order of Assembly Cylinder heads often warp upward in the center. Loosening the center head bolts first will tend to increase the warpage, especially if the head is being removed to replace a head gasket because of overheating. Always follow the torque table backwards, starting with the highest-number bolt and working toward the lowest number. In other words, always loosen fasteners starting at the end or outside of the component and work toward the inside or center of the component.

• A normal combustion chamber is coated with a layer of hard, light-colored deposits. • If the combustion chamber has been running too hot, the deposits will be very thin and white.

FIGURE 28–7 Keeping the pushrods and the lifters sorted by cylinder, including the spark plugs, is a wise way to proceed when disassembling the cylinder heads.

OVERHEAD CAMSHAFT (OHC) ENGINE DISASSEMBLY (if equipped) are off of V-type engines, the technician has another opportunity to examine the interior of the engine. On some V-type engines, it is possible to see the condition of the cam at the bottom of the lifter valley. STEP 4

The lifters can be removed at this time if they are causing the problem or if the engine valve train is to be serviced.

STEP 5

Remove the cylinder head bolts (also called cap screws) following the reverse of the installation procedure. Loosening the fasteners at the ends of the cylinder head first, then working toward the center, helps reduce the chance of warpage to the cylinder head. Be sure to notice and mark the head bolt locations as they are often different lengths depending on their location in the head. Carefully lift the head from the block deck. If the head gasket is stuck, carefully pry the head to loosen the gasket. Use care not to scratch the block or head machined surfaces. The combustion chamber in the head and the top of the piston should be given a thorough visual examination. SEE FIGURE 28–8. • Check the cylinder head and head gasket for signs of leakage.

Disassembling an overhead camshaft engine differs from a camin-block (OHV) engine. Check service information for the specified disassembly procedure for the engine being serviced. Read, understand, and follow all safety notices and warnings included in the instructions to help avoid causing damage to parts or components during the disassembly process. The usual steps include: STEP 1

Remove the intake and exhaust manifolds if they have not already been removed and bag and tag all fasteners.

STEP 2

Remove the crankshaft harmonic balancer pulley that will allow access to the timing chain or belt cover.

STEP 3

Remove the timing belt/chain cover(s) and then the timing belt(s) or chain(s).

STEP 4

With most overhead camshaft engines, the camshaft(s) must be removed before removing the cylinder head due to location of the head bolts.

STEP 5

Remove the cylinder head by removing the cylinder head bolts in the opposite order of assembly. This means to loosen the outermost fasteners first, then work toward the center of the cylinder head.

STEP 6

Carefully lift the cylinder head from the block.

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CYLINDER RIDGE NUMBERS STAMPED ON CONNECTING ROD AND ROD CAP

.009" WEAR UPPER END OF TOP RING TRAVEL .0003" WEAR UPPER END OF PISTON SKIRT TRAVEL

LOWER END OF BOTTOM RING TRAVEL

FIGURE 28–9 These connecting rods were numbered from the factory. If they are not, then they should be marked.

AREA OF GREATEST WEAR

PISTON SKIRT TRAVELS IN AREA OF LEAST WEAR

FIGURE 28–10 Most of the cylinder wear is on the top inch just below the cylinder ridge. This wear is due to the heat and combustion pressures that occur when the piston is near the top of the cylinder.

DISASSEMBLY OF THE SHORT BLOCK REMOVING THE OIL PAN

To remove the oil pan, turn the

engine upside down. NOTE: Some engine builders prefer to remove the oil pan before turning it upside down so the technician can see the oil pan deposits first. Deposits are a good indication of the condition and care taken of the engine. Heavy sludge indicates infrequent oil changes; hard carbon indicates overheating. The oil pump pickup screen should be checked to see how much plugging exists.

MARKING CONNECTING RODS AND CAPS The connecting rod caps should be marked (numbered) so that they can be reassembled in exactly the same position. If the connecting rods are not marked from the factory, then they should be marked using a number stamp, electric pencil, or permanent marker. SEE FIGURE 28–9. CAUTION: Some vehicle manufacturers warn not to use a punch or an electric pencil on powdered metal connection rods. Use only a permanent marker to label powdered metal rods. If in doubt as to the type of rod that is in the engine, use a marker to be safe.

REMOVING THE CYLINDER RIDGE

Before the pistons can be removed from the block, the ridge must be removed. Piston wear against the cylinder wall leaves an upper ridge, because the top ring does not travel all the way to the top of the cylinder. Ridge removal is necessary to avoid catching a ring on the ridge and breaking the piston. SEE FIGURE 28–10. The ridge is removed with a cutting tool that has a guide to help prevent accidental cutting below the ridge. SEE FIGURE 28–11.

FIGURE 28–11 This ridge is being removed with one type of ridge reamer before the piston assemblies are removed from the engine.

TECH TIP Measure the Cylinder Bore Before Further Disassembly As soon as the cylinder head has been removed from the engine, take a measurement of the cylinder bore. This is done for the following reasons. • To verify that the engine size is the same as specified by the vehicle identification number (VIN) • To measure the bore and compare it to factory specifications, to help the technician determine if the cylinder(s) are too worn to use or cannot be restored

STEP 2

Remove connecting rod nuts from the rod so that the rod cap with its bearing half can be removed.

STEP 3

Fit the rod bolts with protectors to keep the bolt threads from damaging the crankshaft journals, and then carefully remove the piston and rod assemblies.

STEP 4

After removal of each piston, replace the rod cap and nuts to avoid losing or mismatching them.

PISTON REMOVAL

Removing the piston and rod assembly includes the following steps. STEP 1

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Rotate the engine until the piston that is to be removed is at bottom dead center (BDC).

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FIGURE 28–12 Puller being used to pull the vibration damper from the crankshaft.

ROTATING ENGINE ASSEMBLIES REMOVAL HARMONIC BALANCER REMOVAL The next step after the water pump has been removed is to remove the crankshaft vibration damper (also called a harmonic balancer). The bolt and washer that hold the damper are removed. The damper should be removed only with a threaded puller. SEE FIGURE 28–12. If a hook-type puller is used around the edge of the damper, it may pull the damper ring from the hub. If this happens, the damper assembly will have to be replaced with a new assembly. With the damper assembly off, the timing cover can be removed, exposing the timing gear or timing chain. Examine these parts for excessive wear and looseness. SEE FIGURE 28–13. Bolted cam sprockets can be removed to free the timing chain. On some engines this will require removal of the crankshaft gear at the same time. Pressed-on gears and sprockets are removed from the shaft only if they are faulty. They are removed after the camshaft is removed from the block. It is necessary to remove the camshaft thrust plate retaining screws when they are used. CAMSHAFT REMOVAL The camshaft and balance shafts, if equipped, can be removed at this time, or they can be removed after the crankshaft is out. For best results, insert a long bolt into one of the camshaft threaded holes to serve as handles for removing (or installing) a camshaft. It must be carefully eased from the engine to avoid damaging the cam bearings or cam lobes. This is done most easily with the front of the engine pointing up. Bearing surfaces are soft and scratch easily, and the cam lobes are hard and can chip easily. CRANKSHAFT AND MAIN BEARING REMOVAL

The main bearing caps should be checked for position markings before they are removed. If they are not marked, use steel number stamps to mark them and also be sure to indicate which side of each main cap faces to the front of the engine. SEE FIGURE 28–14. They have been machined in place and will not fit perfectly in any other location. After marking, they can be removed to free the crankshaft. When the crankshaft is removed, the main bearing caps and bearings are reinstalled on the block to reduce the chance of damage to the caps.